THE  LIBRARY 

OF 

THE  UNIVERSITY 

OF  CALIFORNIA 

LOS  ANGELES 

GIFT  OF 

SAN  FRANCISCO 
COUNTY  MEDICAL  SOCIETY 


HETEROPHORIAS  AND 
INSUFFICIENCIES 


A  CLINICAL  STUDY 


BY 

H.  H.  SEABROOK,  M.D., 

SURGEON,  NEW  YORK  EYE  AND  EAR  INFIRMARY,  ETC. 


Cbc  Ikmchcrbocfccr  press 
1900 


Library 

WtO 


HETEROPHORIAS  AND 
INSUFFICIENCIES 

A  CLINICAL  STUDY. 


CHAPTER   I. 

GENERAL   CONSIDERATIONS  AND    METHODS   OF 
TESTING. 

TH  E  class  of  cases  to  be  considered  here  has  been 
recognized  as  having  had  an  existence  since 
\^»  the  dawn  of  modern  ophthalmology.     Von  Graefe  at- 
tempted to  solve  the  problems  they  presented,  and 
:    although  he  furnished  some  valuable  ideas  for  his 
:    successors  to  work  upon,  his  knowledge  upon  the 
tf    subject  would  be  a  poor  equipment  for  an  ophthal- 
.*    mologist  of  to-day.     Donders  saw  the  fallacies  of  the 
work   being   done   in    this   field,  solved   in  general 
Jfc    terms  the  problem  of   accommodative    asthenopia, 


624398 


2  Hctcrophorias  and  Insufficiencies. 

and  found  that  "  as  soon  as  insufficiency  of  the  in- 
ternal or  external  recti  muscles  in  binocular  vision 
threatens  to  give  rise  to  muscular  asthenopia,  it  is  of 
importance  that  the  mutual  distance  of  the  glasses 
should  not  aggravate  this  but  rather  counteract 
it."  If  spherical  glasses  are  insufficient,  we  are  to 
combine  with  prisms  or  operate  according  to 
Von  Graefe.  There  is  agreement  with  Helmholtz's 
statement  that  displacement  of  glasses  in  a  vertical 
direction  causes  more  asthenopia  than  the  same 
amount  of  lateral  displacement.  Except  for  the  op- 
erative method  indicated,  the  statements  here  made 
are  entirely  sound,  but  cannot  be  said  to  suffer  from 
over-elaboration ;  they  seem,  however,  sufficient  to 
more  than  cover  what  is  usually  done  for  muscular 
asthenopia  to-day  in  practice  upon  the  European 
continent.  In  England  signs  of  interest  began  to  be 
manifested  regarding  these  cases  over  fifteen  years 
ago,  and  thanks  to  the  work  of  Maddox  and  others 
many  principles  of  value  were  evolved.  Previous  to 
this,  Stevens  in  America  had  succeeded  in  attracting 
attention  by  means  of  his  work,  his  highly  enthusi- 
astic followers,  and  his  bitter  opponents.  A  portion 
of  his  nomenclature  came  into  general  use,  and  is 
here  followed.  Orthophoria,  muscular  balance  ;  het- 
erophoria,  tendency  to  deviation ;  esophoria,  conver- 
gence tendency  ;  exophoria,  divergence  tendency  ; 
hyperphoria,  upward  tendency.  These  terms  were 


A  Clinical  Study.  3 

taken  to  be  equivalent  to  and  supersede  the  old  ones 
of  insufficiency  of  the  interni  and  externi,  even 
Duane,  whose  masterly  classification  of  these  condi- 
tions has  earned  deserved  recognition,  taking  this 
view  ;  yet  heterophoria  means  merely  a  tendency  of 
the  fixation  lines  away  from  the  object  of  fixation, 
while  insufficiency  means  lack  of  power.  The  old 
terms  for  exophoria  and  esophoria  were  dynamical 
divergence  and  convergence.  It  is  the  intention  of 
the  writer  to  show  that  certain  forms  of  heterophoria 
may  be  due  to  errors  of  refraction  or  other  optical 
defects,  others  to  habit,  others  to  the  nervous  sys- 
tem, and  others  still  to  muscular  spasm,  excess,  or 
insufficiency.  Much  has  been  written  upon  this 
subject  in  addition  to  that  so  briefly  mentioned, 
some  of  it  of  value,  and  the  writer  proposes  to  treat 
all  of  the  authors  in  the  most  impartial  manner,  as 
he  appropriates  their  ideas  whenever  he  can  make 
use  of  them,  without  regard  to  their  source.  He  has 
no  instruments  to  exploit,  no  special  method  of  treat- 
ment to  push,  no  new  general  disease  which  he  has 
cured  through  the  eye  muscles.  If,  in  spite  of  this, 
an  original  idea  or  so  should  creep  in  among  the 
others,  anybody  is  welcome  to  use  it  as  his  own. 

In  discussing  the  question  of  correcting  the  refrac- 
tion except  as  incidental  to  the  treatment  of  muscu- 
lar anomalies,  there  is  of  course  no  intention  to 
belittle  this  very  important  consideration  in  the 


4  Heterophorias  and  Insufficiencies. 

treatment  of  eye  strain.  Important  as  this  branch 
of  the  subject  undoubtedly  is,  correction  of  the  re- 
fraction may  be  carried  to  the  point  of  absurdity. 
When  a  patient  with  undoubted  exophoria  and  in- 
sufficiency of  the  interni  complains  of  severe  head- 
ache, dizziness  and  nausea,  excited  or  increased 
when  convergence  is  attempted,  it  is  perfectly  silly 
to  correct  .12  or  .25  D.  of  hypermetropia  in  such 
eyes,  and  yet  many  have  done  such  things. 

In  studying  the  effect  of  correction  of  the  refrac- 
tion upon  the  ocular  muscles,  it  is  absolutely  neces- 
sary to  separate  this  secondary  effect  of  glasses  from 
the  prismatic  effect  of  a  decentred  lens.  In  order 
that  the  optical  centre  of  a  lens  may  be  found,  the 
lens  should  be  held  in  front  of  a  horizontal  line  in 
such  a  position  that  the  line  is  continuous  through 
the  glass  without  deviation  at  either  edge.  The 
position  of  this  line  is  then  marked  upon  the  glass 
and  the  process  repeated  at  right  angles  to  the  first 
position ;  the  lines  cross  at  the  optical  centre  and 
show  in  a  sphero-cylindrical  lens  the  axis  of  the  cyl- 
inder and  the  maximum  curve  at  right  angles  to  it. 
In  a  simple  cylinder  the  axis  only  can  be  found,  as 
there  is  no  prismatic  displacement  of  a  line  at  right 
angles  to  the  axis  ;  a  cylinder  with  horizontal  axis 
cannot  be  decentred  horizontally,  and  similarly  with 
the  axis  in  other  meridians.  Two  lines  crossing  at 
right  angles  may  be  used  to  find  the  optical  centre 


A  Clinical  Study.  5 

instead  of  the  above-described  method,  or  the  lens 
may  be  held  in  front  of  an  object,  as  a  candle  flame, 
in  such  a  position  that  the  reflected  images  from  the 
surfaces  of  the  glass  are  superimposed,  when  the  po- 
sition of  the  images  shows  the  optical  centre.  The 
last  method  may  be  used  for  rapid  verification 
under  certain  circumstances,  but  I  prefer  the  first  for 
several  reasons.  The  base  and  apex  of  a  prism  are 
marked  by  a  line  continuous  through  the  glass,  just 
as  the  axis  of  a  cylinder  is.  When  the  cylinder  is 
revolved  upon  its  centre,  we  notice  a  peculiarity  of 
prismatic  action  due  to  the  varying  curves,  which  re- 
sults in  torsion  of  lines  oblique  to  the  axis,  being 
most  marked  at  an  inclination  of  45°.  While  there 
are  causes  for  the  distortion  of  objects  caused  by 
glasses  other  than  simple  prismatic  effect,  yet  this 
prismatic  action  of  the  transparent  cylinder  has  not 
only  an  important  bearing  upon  the  asthenopia  pro- 
duced by  cylindrical  lenses,  but,  taken  in  connection 
with  other  prismatic  effects  of  curved  surfaces  and 
applied  to  the  human  eye  with  its  frequently  de- 
centred  astigmatic  refractive  media,  it  throws  an 
entirely  new  light  upon  many  observations  in  physio- 
logical optics  and  opens  up  a  new  field  in  the  ex- 
planation of  muscular  anomalies.  A  very  plausible 
connection  could  be  shown  between  apparent  diver- 
gence and  convergence,  the  decentred  biconvex 
lens  system  between  the  anterior  corneal  surface  and 


6  Heterophorias  and  Insufficiencies. 

the  posterior  surface  of  the  crystalline  lens,  and  con- 
vergent and  divergent  squint ;  its  bearing  upon  the 
subject  in  hand  will  be  shown  later. 

The  primary  position  of  a  pair  of  glasses  in  front 
of  the  eyes  when  it  is  desired  to  study  their  effects 
upon  the  ocular  muscles  is  with  the  optical  centres 
in  the  lines  of  fixation.  This  position  can  be  ob- 
tained with  considerable  accuracy  by  sighting  ;  that 
is,  by  making  each  examined  eye  fix  the  examiner's, 
when  the  optical  centre  of  the  glass  is  placed  in  the 
line  which  seems  to  correspond  to  the  line  of  fixation 
of  the  former  and  the  line  of  vision  of  the  latter.  If 
there  is  a  question  as  to  the  correctness  of  this,  discs 
with  vertical  stenopaeic  slits  may  be  placed  in  an 
adjustable  frame,  and  the  distance  between  their 
centres  measured  when  both  eyes  can  see  through 
the  slits  at  the  same  time.  This  distance  between 
the  optical  centres  (o.  c.)  should  not  be  confounded 
with  the  distance  between  the  geometrical  centres 
of  glasses  to  be  worn  (p.  d.),  which  should  come  op- 
posite the  pupils  for  the  sake  of  appearance  and 
because  there  will  be  less  annoyance  to  the  patient 
from  the  refraction  and  reflection  at  the  edges  of  the 
lenses  when  they  are  symmetrical  with  the  pupil. 

The  prismatic  effect  of  a  decentred  spherical  lens 
is  obtained  by  multiplying  the  distance  between  the 
optical  and  geometrical  centres,  taken  in  centimetres 
and  tenths,  by  the  dioptric  strength  of  the  lens. 


A  Clinical  Study.  ^ 

Thus,  a  2  D.  lens  decentred  3  mm.  equals  a  .6  D. 
prism,  2.  X  -3  =  .6.  In  a  pair  of  glasses  the  difference 
between  the  primary  and  secondary  position  is  taken. 
Thus,  if  the  glasses  are  60  mm.  o.  c.,  and  the  lines  of 
fixation  cut  them  57  mm.  apart,  the  prismatic  action 
of  a  pair  of  2  D.  lenses  is  .6  D.,  one  half  in  each 
eye.  If  the  number  of  centimetres  of  decentring 
to  produce  a  certain  prism  is  desired,  the  formula 
is  v-~  =  cms.,  in  tenths.  The  base  of  the  prism  is,  of 
course,  toward  the  periphery  of  a  concave  lens, 
toward  the  centre  of  a  convex  one.  If  the  curve  of 
the  lens  and  the  position  of  the  line  of  fixation  are 
kept  in  mind,  or  put  on  paper,  there  can  be  no  con- 
fusion. In  a  cylindrical  lens  the  number  of  dioptrics 
can  be  found  in  any  direction  by  means  of  the  lens 
measure  and  prismatic  action  then  figured  as  for  a 
sphere. 

This  easy  method  of  figuring  the  prismatic  action 
of  a  decentred  lens  is  one  of  the  merits  of  the  prism 
dioptry  system  proposed  by  Mr.  Charles  Prentice,  a 
layman,  and  adopted  by  many  manufacturing  opti- 
cians throughout  the  country  on  account  of  its  sim- 
plicity and  accuracy  when  applied  to  the  manufacture 
of  prisms.  I  began  to  use  it  soon  after  it  was  first 
suggested.  The  unit  is  the  prismatic  power  which 
causes  I  cm.  of  light  deviation  at  I  metre.  A  lens  of 
i  D.  refractive  power  decentred  I  cm.  =  I  P.  D. 
(A  D.  or  D.),  i.X  i.=  i.  The  best  scale  I  know  for 


8  Heterophorias  and  Insufficiencies. 

measuring  prisms  in  this  system  is  that  of  Dr.  Ziegler. 
I  propose  to  speak  of  heterophorias  in  terms  of  prism 
dioptrics,  just  as  we  speak  of  hypermetropia  and 
myopia  in  terms  of  the  correcting  glass.  It  is  not 
necessary  in  either  case  to  add  dioptrics  or  D.  to  the 
figures  in  decimals  which  designate  the  strength  of 
the  glasses,  and  it  will  generally  be  omitted  in  the 
following  pages. 

There  are  a  few  things  regarding  the  action  of 
prisms  necessary  to  remember  in  clinical  work. 
Prisms  beyond  a  certain  strength  can  not  be  used  in 
correcting  anomalies  of  the  ocular  muscles  for  several 
reasons,  some  relating  to  the  effect  upon  the  muscu- 
lar action,  others  to  mental  effect  upon  the  patient, 
and  yet  others  to  distortion  due  to  prismatic  astig- 
matism from  the  varying  ratio  between  the  angles  of 
incidence  and  refraction.  There  is  a  position  of 
minimum  deviation  in  which  a  ray  of  light  passes 
symmetrically  through  a  prism  and  other  rays  suffer 
greater  deflection.  In  testing  for  an  object  in  the 
direction  of  the  line  of  fixation,  prisms  should  be 
placed  with  the  surface  toward  the  eye  perpendicu- 
lar to  that  line,  in  order  to  secure  as  nearly  as  possi- 
ble the  position  of  minimum  deviation.  The  position 
of  the  prism  may  assume  some  importance  in  the  case 
of  a  vertical  prism,  as,  if  this  is  placed  in  the  posi- 
tion of  minimum  deviation  for  distance,  its  action  is 
stronger  for  near  points,  the  increase  amounting  to 


A  Clinical  Study.  9 

about  one-tenth  of  its  strength  for  the  nearest  point 
at  which  the  eyes  are  likely  to  be  used. 

As  will  be  shown  later,  patients  with  inefficient 
ocular  muscles  do  not  bear  prisms  as  well  as  those 
with  strong  muscular  action ;  stronger  prisms  may 
be  worn  base  in  for  near  work  than  base  out  for  dis- 
tance, and  with  axis  horizontal  than  vertical,  and  a 
3  D.  prism  over  each  eye  is  about  the  limit  of 
strength  under  favorable  conditions. 

Secondary  images  due  to  reflection  from  the  sur- 
faces of  the  glass  cause  more  annoyance  in  glasses 
containing  prisms  than  in  those  without  them,  but 
the  colors  due  to  dispersion,  diminution  in  size  and 
change  of  shape  of  an  object,  occur  to  a  considerable 
extent  only  when  a  strong  prism  is  placed  before 
one  eye,  as  in  testing  muscular  power,  or  at  least  are 
remarked  upon  by  patients  mostly  under  this  con- 
dition. 

The  eye  moves  toward  the  apex  of  a  prism  in  or- 
der to  overcome  the  deviation  of  rays  of  light 
toward  the  base,  and  when  it  is  unable  to  do  this 
diplopia  results,  with  the  image  from  the  eye  before 
which  the  prism  is  placed  in  the  direction  of  the 
apex.  The  action  of  the  interni  in  overcoming 
prisms  base  out  is  called  adduction,  the  externi  with 
prisms  base  in,  abduction.  These  terms  are  easily 
confounded,  and  the  mind  becomes  so  confused  and 
fatigued  by  them  that  I  propose  to  use  instead  the 


io  Heterophorias  and  Insufficiencies. 

terms  convergence  and  divergence.  This  can  cause 
no  confusion  as  the  amount  is  always  given  in 
terms  of  measurement.  P.  D's  of  convergence  and 
divergence  cannot  possibly  be  confounded  with 
metre-angles  or  degrees,  and  those  who  use  the  term 
degrees,  except  as  applied  to  perimetric  measure- 
ments, cannot  be  cast  into  any  more  confusion  by 
the  innovation  than  that  under  which  they  now  are 
laboring. 

There  is  one  point  upon  which  there  is  agreement 
among  all  investigators  in  this  direction :  it  is  that 
abduction  or  divergence  for  distance  with  well  bal- 
anced and  strong  eye  muscles  should  be  7.  or  8- 
[These  figures  are  the  same  whether  the  old  degree 
system,  dioptry,  or  centrad  is  used.  It  is  beside  the 
purpose  of  this  treatise  to  argue  regarding  these  sys- 
tems and  the  new  system  in  degrees  of  Landolt. 
Whatever  its  demerits,  the  dioptric  system  has  been 
(unofficially)  adopted.]  The  student  who  finds  that 
his  investigations  seem  to  contradict  this  standard 
for  divergence  should  doubt  the  accuracy  of  his  ob- 
servations ;  with  an  abducting  prism  the  double 
images  may  easily  pass  unnoticed  when  they  first 
appear  and  then  suddenly  be  observed  a  consider- 
able distance  apart  at  the  time  a  stronger  prism  than 
represents  divergence  is  being  used.  In  such  a  case 
prisms  of  gradually  decreasing  strength  should  be 
used  until  single  vision  results,  then  gradually 


A  Clinical  Study.  1 1 

increased  again.  After  some  experience  the  exam- 
iner will  begin  with  the  prism  which  is  to  his  mind 
most  likely  to  represent  the  divergence  to  be  ex- 
pected from  the  examinations  previously  made  of  the 
refraction  and  muscular  balance.  Until  this  experi- 
ence is  acquired  it  is  well  to  start  with  a  prism  of  6., 
7.,  8.,  or  9.  It  has  already  been  said  that  divergence 
which  varies  from  7.  or  8.  may  be  considered  ab- 
normal. A  certain  number  of  cases  show  but  6.,  in 
which  the  only  criticism  is  that  divergence  and  con- 
vergence are  neither  of  them  at  their  best.  In  other 
words,  amplitude  of  convergence  is  slightly  below 
the  standard,  and  there  is  no  other  defect.  An  oc- 
casional case  may  be  found  in  which  the  amplitude 
of  convergence  is  so  great  that  divergence  of  9.  or 
even  10.  is  equalized  by  correspondingly  strong  con- 
vergence and  muscular  balance  is  good.  Such  cases 
are  liable  to  develop  exophoria  later,  but  for  the 
time  being  are  sometimes  to  be  complimented  upon 
their  strong  ocular  muscles.  Cases  like  this  are 
perhaps  not  so  infrequent  as  would  appear  from 
our  histories.  Persons  with  ocular  muscles  of  that 
sort  would  not  be  apt  to  be  weak  or  neurasthenic, 
and  would  hardly  be  bothered  by  trivial  errors  of 
refraction. 

When  it  is  said  that  divergence  for  distant  vision 
should  be  7.  or  8.,  what  is  really  meant  is  that  this  is 
what  should  be  shown  by  the  candle  test  at  a 


1 2  Heterophorias  and  Insufficiencies. 

distance  of  about  twenty  feet,  which  is  the  usual  test. 
It  is  in  reality  about  I.  more  than  the  actual  power 
of  divergence  for  infinity,  as  I  D.  of  convergence  is 
necessary  for  binocular  fixation  at  twenty  feet.  It 
is  fortunate  that  there  should  be  such  a  definite 
standard  of  divergence  for  distance,  since  the  power 
of  divergence  for  distant  vision  is  an  important  mat- 
ter ;  divergence  power  for  any  near  point  theoretic- 
ally would  equal  the  amount  required  to  bring  the 
lines  of  fixation  parallel,  added  to  that  which  is  still 
possible  with  parallel  fixation  lines  when  the  eyes 
are  adjusted  for  infinity.  This  total  is  obscured  in 
making  a  test  at  a  near  point  by  the  accommodative 
convergence  and  certain  other  factors,  but  while 
neither  so  definite  nor  important  as  divergence  ob- 
tained for  distance,  it  is  a  help  in  comparing  the 
variations  of  the  muscular  action  for  near  and  far. 
At  about  thirteen  inches  (taken  as  the  average  read- 
ing distance)  the  prism  test  shows  generally  some  6 
to  8  D's  more  of  divergence  than  is  shown  by  the 
test  at  twenty  feet,  the  difference  being  less  than 
this  in  cases  of  esophoria  without  insufficiency  of 
convergence,  greater  in  some  cases  of  exophoria. 
Where  divergence  at  thirteen  inches  is  18.  or  more, 
insufficiency  of  convergence  power  at  that  distance 
is  almost  sure  to  be  present. 

Convergence  power  for  near  work  is  of  far  more 
importance  than  it   is  for  distance,  which  is  also 


A  Clinical  Study.  13 

fortunate,  as  the  prism  test  for  convergence  at  a  dis- 
tance is  very  variable.  This  variability  is  due  mostly 
to  the  much  greater  difficulty  some  persons  have 
of  disassociating  convergence  and  accommodation 
than  others.  If  the  only  precaution  taken  in  making 
the  test  is  that  of  dividing  the  prisms  between  the 
examined  eyes  (a  prism  over  one  eye  not  only  causes 
dissimilar  images  but  often  convergence  in  the 
armed  eye  alone,  the  other  fixing),  the  proportion 
between  convergence  and  divergence  in  eyes  with 
orthophoria  is  apt  to  be  as  low  as  three  to  one.  Con- 
vergence 1 8.,  divergence  6.  is  about  the  limit  for  use- 
ful ocular  muscles  on  the  one  hand,  while  70.  versus 
10.  or  even  more  can  in  rare  instances  be  found 
among  the  strong  muscles. 

Convergence  does  not  represent  the  strength  of  the 
interni  alone,  but  the  nervous  energy  put  into  them 
as  well.  In  testing  this  power,  being  of  too  impa- 
tient a  nature  to  wait  for  prism  exercises  or  other 
slow  methods,  I  have  my  patients  fix  a  finger,  or  a 
lead  pencil,  which  is  gradually  approached  while  the 
eyes  are  armed  with  converging  prisms,  and  often 
with  the  exclamation, "  Oh,  that  is  what  you  want  me 
to  do,"  they  proceed  to  converge  at  distance  at  least 
half  as  much  again  as  they  had  succeeded  in  doing 
but  a  moment  before.  The  rapidity  and  simplicity 
of  this  will  absolutely  prevent  its  acceptance  as  a 
cure,  so  I  shall  not  elevate  it  to  the  dignity  of  a 


14  Heterophorias  and  Insufficiencies. 

method  by  giving  it  a  name,  as  the  principle  itself  is 
already  in  use  under  many  high-sounding  titles. 

A  moment's  reflection  will  show  anyone  that  the 
prism  test  at  distance  does  not  necessarily  represent 
the  real  convergence  power  as  shown  by  the  near 
point  for  convergence.  For  the  latter  test  I  use  a  lead 
pencil  or  a  penholder,  as  being  an  object  which  is 
always  at  hand  during  an  examination,  necessitates 
accommodation  on  the  part  of  the  patient  in  order 
that  it  shall  be  clearly  seen,  and  allows  the  examiner 
to  watch  the  action  of  the  eyes  without  distracting 
his  attention.  The  ease  with  which  convergence  for 
the  near  point  is  accomplished,  and  the  steadiness 
with  which  the  eyes  hold  an  object,  are  of  more  im- 
portance than  the  exact  measure  of  its  distance  from 
the  eyes,  and  the  sensations  produced  by  this  mus- 
cular action,  with  the  attitude  of  the  patient  regard- 
ing them,  are  valuable  diagnostic  indications.  I 
would,  moreover,  as  soon  trust  my  observation  as  to 
when  convergence  is  no  longer  possible  as  a  patient's 
statement  regarding  the  production  of  diplopia. 
Tests  for  the  near  point  usually  will  show  more 
power  of  convergence  than  the  prism  test  at  distance, 
because  in  the  latter  instance  the  convergence 
without  accommodation  is  an  unwonted,  as  it  is  usu- 
ally an  unnecessary,  accomplishment.  Teaching  a 
patient  how  to  converge  with  prisms  is  simply  train- 
ing for  a  test,  and  has  something  of  the  same  relation 


A  Clinical  Study.  15 

to  a  cure  of  weak  convergence  as  training  a  sensitive 
throat  for  the  tongue  depressor  has  to  the  treatment 
of  hypertrophied  tonsils. 

The  near  point  of  convergence  varies  with  the 
refraction  and  becomes  more  and  more  distant  as 
age  advances  and  accommodation  and  the  interni 
become  weaker.  Undoubtedly  valuable  as  the  test 
for  the  near  point  of  convergence  may  be,  I  confine 
my  use  of  it  mostly  to  certain  purposes  already 
mentioned,  and  as  a  check  upon  other  tests.  Thus 
if  convergence  with  prisms  for  a  distance  seems 
below  normal,  I  should  reject  a  diagnosis  of  insuffi- 
ciency of  the  interni,  or  of  excess  of  the  externi, 
if  the  same  eyes  showed  easy  and  comfortable 
convergence  up  to  two  inches  or  less  from  the 
root  of  the  nose,  with  or  without  the  correction 
of  the  refraction.  The  prism  test  for  conver- 
gence at  the  reading  distance  is  unsatisfactory, 
although  some  information  may  be  gained  thereby, 
as  in  cases  in  which  hyperphoria  occurs  only  with 
convergence. 

Sursumduction,  or  upward  movement  of  an  eye,  is 
tested  on  the  same  principle  as  convergence  and 
divergence  :  right  sursumduction  with  the  prism  base 
down  right  eye,  or  base  up  left  eye  ;  left  sursumduc- 
tion base  down  left  eye,  base  up  right  eye.  It  is  hardly 
necessary  to  call  attention  to  the  necessity  of  verify- 
ing the  base  apex  line  of  the  prism  and  having  this 


1 6  Heterophorias  and  Insufficiencies. 

axis  exactly  horizontal  or  vertical  in  the  above 
mentioned  tests. 

Although  it  has  been  convenient  to  consider  here 
the  muscular  strength  as  shown  in  divergence  and 
convergence  before  the  muscular  balance  or  tendency 
to  deviation,  the  latter  should  be  tested  before  the 
former  and  preferably  after  examination  of  the  re- 
fraction. The  test  for  balance  which  is  most  time- 
honored  is  that  by  which  vertical  prisms  produce 
diplopia,  when  if  the  images  have  a  homonymous 
or  crossed  position  as  regards  each  other  the  correct- 
ing prism  which  brings  them  into  equilibrium  is  con- 
sidered the  measure  of  the  esophoria  or  exophoria. 
This  test  should  be  made  at  a  distant  and  near  point, 
first  without,  then  with,  the  refraction  corrected.  I 
give  the  conclusions  for  a  near  point  based  upon 
tests  at  13  inches,  as  this  is  the  distance  I  have 
chosen  for  years,  although  now  satisfied  that  it  is 
somewhat  too  near  for  most  cases.  The  near  test 
would  be  best  taken  at  reading  distance,  which 
varies  in  different  individuals. 

The  test  for  equilibrium  with  prisms  has  been  per- 
fected, especially  by  Stevens,  and  has  resulted  in  the 
phorometer  with  its  two  prisms  of  5  D's  base  in, 
which  can  be  rotated,  after  the  test  for  vertical 
equilibrium  has  been  obtained,  for  the  test  of 
the  lateral  tendency,  and  shows  the  amount  and 
nature  of  the  deviation  upon  its  anterior  surface 


A  Clinical  Study.  1 7 

in  prism  dioptrics  when  the  images  show  equi- 
librium. It  thus  gives  the  novice  information 
of  the  deviation  with  which  he  has  to  deal  with 
some  certainty,  as  he  can  hardly  turn  the  instru- 
ment upside  down  or  otherwise  misplace  it  in 
making  a  test.  When  the  axis  of  the  prism  is  hori- 
zontal, if  single  vision  still  obtains  it  is  a  fair  con- 
clusion that  divergence  is  excessive,  and  another 
prism  may  be  added  in  order  to  obtain  the  lateral 
images,  the  prisms  in  the  phorometer  only  being 
rotated  in  obtaining  the  measurements.  An  arm 
upon  the  instrument  is  very  handy  for  getting  the 
muscular  balance  at  a  near  point,  although  the  test 
object  is  more  horizontal  to  the  eyes  than  the  position 
of  the  other  objects  most  often  seen  at  this  distance 
in  ordinary  work.  As  a  rule,  deviations  remain  latent 
with  this  test  to  an  extent  that  they  do  not  with  the 
rod  test,  although  occasionally  the  reverse  is  true. 

The  Maddox  glass  rod,  or  series  of  rods,  will  pro- 
duce a  line  of  light  at  right  angles  to  the  axis  when 
placed  before  an  eye.  This  test  has  the  advantage  of 
indicating  the  fixing  eye  (the  unarmed  one)  and  al- 
lows it  to  be  changed  at  will  by  changing  the  rod  from 
one  eye  to  the  other.  When  the  correcting  prism 
is  obtained  its  amount  and  direction  are  patent,  thus 
saving  the  beginner  in  ophthalmology  some  mental 
effort  in  ordering  correcting  prisms.  When  a  devia- 
tion has  been  corrected  with  a  prism  in  one  direction 


1 8  Heterophorias  and  Insufficiencies. 

the  rod  test  will  show  the  effect  upon  the  deviation 
at  right  angles  to  it,  a  very  important  consideration 
in  certain  instances,  as  when  with  a  correcting  prism 
for  hyperphoria  we  wish  to  test  exophoria  or  eso- 
phoria  as  compared  to  the  same  deviation  before 
the  correction.  The  rod  test  also  allows  of  an  ex- 
amination toward  the  periphery  of  the  field  more 
accurate  than  that  of  the  phorometer,  when  we 
wish  to  see  if  the  deviations  are  comitant,  but  is  of 
no  definite  use  in  testing  for  reading  distance.  I 
can  hardly  see  how  either  of  these  tests  can  be 
dispensed  with. 

The  old  screen  test,  in  which  one  eye  is  covered, 
then  uncovered,  and  its  deviation  noted  while  the 
other  fixes,  was  in  my  hands  so  contradictory  and 
unreliable  long  ago,  that  when  Duane  modified  its 
use  by  adding  a  subjective  element,  giving  the  paral- 
lax test,  I  lacked  sufficient  confidence  in  the  latter  to 
use  it,  in  which  I  may  be  wrong.  Maddox  rejected 
the  double  prism  with  bases  meeting  at  the  centre 
for  the  rod  test,  and  various  attempts  have  been 
made  to  revive  its  use  for  certain  purposes,  with  but 
little  success. 

Having  attempted  to  indicate  the  methods  of  ex- 
amination which  were  followed  in  obtaining  the 
clinical  data  here  used,  I  shall  treat  the  subject  of 
heterophorias  under  the  following  heads:  Hyper- 
phoria; Esophoria,  first,  the  accommodative,  second, 


A  Clinical  Study.  19 

esophoria  from  habit,  lastly,  esophoria  from  insuffi- 
ciency of  the  externi  or  excess  of  the  interni;  Exo- 
phoria,  accommodative  and  muscular;  and  lastly 
Insufficiency  of  Convergence,  Inefficiency  of  the  Ocular 
Muscles,  or  Neurasthenic  Muscular  Asthenopia.  It 
may  be  observed  that  this  class  of  cases  is  not  in- 
tended to  comprise,  except  as  occasional  reference 
may  occur,  those  which  have  spontaneous  diplopia, 
since  I  regard  these  as  either  cases  of  periodic  squint, 
paresis  of  an  ocular  muscle,  or  of  an  associated  move- 
ment ;  neither  are  other  cases  of  evident  strabismus 
without  diplopia  to  be  considered  in  detail.  Although 
in  practice  it  is  difficult  to  draw  the  dividing  line, 
it  is  primarily  my  desire  to  further  definite  knowl- 
edge regarding  a  class  of  cases  in  which  individual 
muscles  may  of  course  be  affected,  yet  the  deviation 
can  only  be  demonstrated  by  the  heterophoria 
shown  with  appropriate  tests. 

It  is  lack  of  definite  knowledge  concerning  devia- 
tions of  both  eyes  above  or  below  the  horizontal 
plane,  or  inclinations  of  the  physiological  vertical 
meridian,  which  prevents  consideration  of  these  sub- 
jects here;  at  present,  although  the  germs  of  ideas 
may  be  working  in  the  brains  of  investigators  upon 
these  subjects,  we  can  hardly  accept  information  as 
definite  where  the  diagnosis  depends  upon  unproven 
points  in  physiology  and  optics  and  treatment  con- 
sists of  muscular  exercises  with  oblique  prisms,  or 


2O  Heterophorias  and  Insufficiencies. 

tenotomy  of  the  upper  half  of  one  lateral  muscle  and 
lower  half  of  its  opponent.  Torsion  will  receive 
some  incidental  consideration  in  dealing  with  muscu- 
lar deviations  connected  with  oblique  astigmatism. 
Before  proceeding  to  the  symptoms  of  the  special 
deviations  to  be  considered,  it  seems  well  to  draw 
attention  to  certain  signs  of  ocular  asthenopia  com- 
mon to  the  different  errors.  They  are  mainly  head- 
ache, dizziness  and  sensations  of  nausea,  pain  in  the 
eyes,  retinal  asthenia  or  hyperesthesia,  congestion 
of  the  palpebral  or  ocular  conjunctiva.  Any  of 
these  may  be  due  to  muscular  anomalies;  pain  in  the 
eyeballs  seems  often  to  occur  from  nutritive  disturb- 
ances, as  may  conjunctival  congestion,  although  the 
latter  is  generally  connected  with  chronic  nasal 
catarrh.  Relief  of  conjunctival  congestion  by 
glasses  may  be  due  to  protection  of  the  eyes  from 
dust  and  chemical  rays  of  light,  has  occurred  with 
plane  glasses,  or  ridiculously  weak  spherical  lenses, 
and  is  no  proof  of  relief  of  eye  strain.  Asthenopic 
symptoms  sometimes  disappear  when  conjunctivi- 
tis is  successfully  treated.  Temporal  headache  is 
usually  due  to  astigmatism,  the  pain  being  most 
severe  on  the  side  of  the  functionally  better  eye, 
this  being  in  men  the  right  when  refraction  and 
vision  are  practically  equal,  because  their  habit  of 
"sighting"  objects  with  this  eye  renders  them 
more  "  right  eyed  "  than  women.  Next  to  eye 


A  Clinical  Study.  2 1 

errors,  tobacco  and  whiskey  in  men,  uterine  trouble 
in  women,  are  the  most  important  factors  in  tem- 
poral headache.  Frontal  headache,  when  dull,  may 
be  due  to  errors  of  refraction,  but  if  severe  and  per- 
sistent suggests  insufficiency  of  the  interni,  or  dis- 
ease of  the  frontal  sinus.  Supra-orbital  neuralgia 
with  tenderness  over  the  nerve  is  usually  unilateral 
and  is  best  treated  with  quinine  unless  the  pain  is 
severe,  radiating  and  persistent, with  much  lacrima- 
tion,  when  it  should  be  referred  to  nasal  obstruction, 
ethmoidal  disease,  or  disease  of  some  other  of  the 
accessory  sinuses.  In  this  latter  condition  there 
may  be  ciliary  pain  and  lowered  intra-ocular  tension. 
A  feeling  of  pressure  over  the  top  of  the  head 
about  the  fronto-parietal  suture  is  from  anaemia,  not 
eye  strain,  and  localized  pain  over  one  parietal  pro- 
tuberance is  not  an  eye  symptom,  although  its  pres- 
ence with  accompanying  tenderness  is  not  a  positive 
diagnostic  sign  of  tumor  of  the  brain,  as  is  sometimes 
stated.  Very  severe  headache  with  vomiting,  com- 
ing on  suddenly  in  persons  who  have  not  been  sub- 
ject to  headaches,  should  always  be  regarded  with 
suspicion,  and  if  persistent,  it  will  perhaps  be  neces- 
sary for  a  diagnosis  between  beginning  cerebral  dis- 
ease and  some  lesion  of  the  digestive  organs  to  wait 
for  further  developments. 

In  "  bilious  attacks  "  there  is  sometimes  paresis 
of  an  ocular  muscle  or  of  an  associated  movement 


2  2  Heterophorias  and  Insufficiencies. 

at  the  time  of  an  attack  which  recurs  with  such 
attacks  for  years,  and  just  such  conditions  of  the 
muscles  may  occur  and  prove  very  misleading  to  the 
oculist  in  cases  of  central  disease  of  the  nervous 
system.  Take,  for  instance,  a  case  of  recurrent 
pachymeningitis  in  an  early  stage,  with  headache 
and  spasm  of  convergence  from  irritation  of  the  con- 
vergence centre,  or  some  other  muscular  trouble 
from  central  lesion  which  resembles  some  muscular 
excess  or  insufficiency  in  which  treatment  usually 
causes  relief,  and  in  such  a  case  relief  to  the  head- 
ache follows  treatment  of  the  eye  muscles.  It  is 
hard  to  avoid  mistakes  in  such  cases,  yet  in  them 
mistakes  are  very  awkward  ;  it  weakens  a  man's  local 
influence  as  an  authority  on  muscular  asthenopia 
when  some  of  his  medical  neighbors  have  attended 
autopsies  upon  the  late  subjects  of  some  of  his  late 
cures,  and  have  not  exercised  that  charity  regarding 
faulty  diagnosis  which  seems  so  often  to  begin  at 
home. 

Pain  in  the  back  of  the  neck,  with  dizziness  and 
nausea,  should  immediately  excite  suspicion  of 
heterophoria,  or  insufficiency  of  the  ocular  muscles. 
Tenderness  over  the  upper  portion  of  the  spine,  or 
the  adjacent  sensory  nerves,  does  not  argue  against 
this.  Similar  pain  with  or  without  general  head- 
ache has  been  known  to  occur  in  disease  of  the 
sphenoidal  and  ethmoidal  sinuses,  is  present  in  brain 


A  Clinical  Study.  23 

disease  and  lesions  of  the  upper  portion  of  the  spine, 
and  is  given  as  a  common  symptom  in  nephritis, 
gout,  stomach,  intestinal  and  liver  diseases,  and 
especially  in  neurasthenia.  In  neurasthenia  these 
symptoms  I  am  satisfied  should  usually  be  referred 
to  the  eyes,  and  in  particular  to  the  ocular  muscles. 
In  cases  in  which  these  symptoms  are  especially 
dwelt  upon  as  diagnostic  of  the  general  nervous  con- 
dition they  are  frequently  helped  by  treatment  of 
eye  strain,  and  I  have  myself  sometimes  in  this 
manner  received  credit  for  curing  neurasthenia 
through  the  eyes,  although  so  far  as  I  know  I  have 
never  seen  a  case  in  which  I  could  positively  and 
justly  claim  any  such  cure.  The  same  holds  good 
in  other  conditions;  the  so-called  gouty  headache, 
and  that  of  nephritis,  may  not  uncommonly  be  re- 
lieved through  eye  treatment,  because  it  was  a 
symptom  of  an  eye  condition,  not  of  gout,  or  kidney 
trouble ;  yet  it  would  be  absurd  to  claim  that  the 
general  disease  had  yielded  to  cylinders,  prisms,  or 
operations  upon  the  eye  muscles.  In  patients  with 
digestive  disturbances,  dizziness  and  nausea  are  more 
apt  to  occur  from  muscular  asthenopia  than  in  other 
cases,  and  these  sensations  no  doubt  occur  frequently 
from  other  causes;  yet  so  many  of  these  cases  are 
more  or  less  benefited  by  eye  treatment  that,  as 
before  mentioned,  the  symptoms  should  excite  sus- 
picion of  eye  strain.  Cases  are  seen  by  the  eye 


24  Heterophorias  and  Insufficiencies. 

specialist  in  which  eye  treatment  has  been  unduly 
delayed  while  general  treatment  was  kept  up  for  eye 
symptoms;  he  has  no  good  opportunity  to  know 
the  other  side  of  the  question. 

The  general  rule  of  double  causation  must  be  ap- 
plied in  these  cases;  there  are  cases  of  eye  devia- 
tions of  the  same  character  as  those  which  cause 
trouble,  which  with  just  as  hard  use  of  the  eyes 
cause  no  asthenopic  symptoms  whatever;  hence 
these  symptoms  must  be  referred,  when  they  occur 
from  eye  errors,  to  such  errors  working  upon  some 
general  condition  susceptible  to  these  symptoms. 

In  the  cases  of  choreic  blepharospasm,  or  spasm 
of  the  facial  muscles,  occurring  with  or  without  other 
choreic  symptoms,  we  are  often  able  to  obtain  relief 
by  treatment  of  heterophoria,  refractive  error,  or 
inflammatory  lesion  of  the  eye  or  appendages,  yet 
in  an  active  stage  of  general  chorea  it  has  seemed 
to  me  that  treatment  of  the  ocular  muscles  some- 
times did  more  harm  than  good ;  prisms  cannot  be 
kept  straight  in  front  of  the  eyes,  the  conditions 
of  the  muscles  are  so  variable  that  it  is  hard  to  tell 
the  nature  of  the  original  tendency,  and  muscle 
operations  are  likely  to  increase  general  nervous 
irritability. 

Dizziness  may  go  on  to  vertigo  in  certain  cases  of 
eye  strain.  Dizziness  and  giddiness  are  used  prop- 
erly as  synonymous  terms,  while  by  vertigo  is  meant 


A  Clinical  Study.  25 

temporary  loss  of  consciousness.  Vertigo  in  this 
sense  is  not  of  frequent  occurrence  from  hetero- 
phoria,  yet  in  occasional  instances  may  take  the 
form  of  fainting  spells  accompanied  by  falling. 
This  is  the  only  kind  of  epilepsy  I  have  personally 
known  to  be  relieved  by  eye  treatment. 

When  a  patient  who  is  in  the  habit  of  reading 
himself  to  sleep  gets  eye  strain  and  cannot  sleep  be- 
cause he  cannot  read  with  comfort,  correction  of  his 
eyes  may  cure  his  insomnia;  yet  eye  treatment  as  a 
cure  for  insomnia  has  usually  failed  in  my  hands. 

I  have  seen  cases  of  nervous  unrest  accompanying 
hyperphoria  or  esophoria  in  which  the  patient  said 
she  felt  like  throwing  herself  out  of  the  window,  and 
met  with  one  case  in  which  there  was  ground  to  be- 
lieve that  the  muscular  deviation  had  actually  helped 
to  cause  a  temporary  suicidal  mania. 

Statements  on  record  to  the  effect  that  severe 
general  headache,  spinal  irritation,  dizziness  and 
nausea  are  common  symptoms  of  refractive  error, 
because  they  disappear  with  correction  of  the  refrac- 
tion, are  to  be  received  with  caution;  a  careful  con- 
sideration of  this  matter  convinces  me  that  these 
symptoms  are  in  such  cases  usually  due  to  hetero- 
phoria  which  is  incidentally  relieved  by  correction 
of  the  refraction,  as  in  accommodative  esophoria. 

Although  the  muscular  deviations  accompany- 
ing errors  of  refraction  will  receive  our  first 


26  Heterophorias  and  Insufficiencies. 

consideration,  the  symptoms  will  not  be  described 
from  this  class  so  much  as  from  those  cases  in  which 
the  refractive  error  played  no  part,  even  if  it  existed. 

It  is  well  to  remember  that  a  headache  which 
wakes  a  patient  from  sleep  is  not  likely  to  be  due  to 
the  eyes,  and  if  it  markedly  decreases  or  disappears 
after  the  patient  has  been  up  and  about  for  a  time 
the  eyes  may  be  eliminated  as  a  causative  factor, 
except  in  a  few  cases  where  there  is  an  eye  error  for 
near  work  which  does  not  cause  strain  for  distant 
vision ;  these  latter  cases  are  free  from  headache 
when  they  do  no  near  work,  but  after  hard  use  of 
the  eyes  in  the  evening  may  wake  with  a  headache 
the  next  morning,  which  passes  off  later  in  the  day. 

It  seems  to  be  accepted  as  a  matter  of  course  that 
the  asthenopia  due  to  muscular  deviations  will  cease 
if  one  eye  only  is  used.  The  closing  of  one  eye 
long  enough  for  diagnostic  purposes  in  the  usual 
class  of  patients  who  suffer  from  asthenopia,  with 
their  weak  nerves  and  strong  desire  for  binocular 
fixation,  is  fraught  with  difficulty,  and  this  principle 
finds  its  application  mostly  in  the  treatment  of  aniso- 
metropia.  There  may  be  an  occasional  case  in  which 
it  is  advisable  to  shut  off  one  eye  with  a  piece  of 
ground  glass  in  a  spectacle  frame  for  the  diagnosis  or 
relief  of  asthenopia,  and  personally  I  prefer  this 
method  to  the  removal  of  an  eye  which  must  neces- 
sarily be  possessed  of  useful  vision,  a  feat  which  I 


A  Clinical  Study.  27 

am  forced  to  believe  by  reliable  authority  has  been 
performed  for  the  relief  of  symptoms  supposed  to 
be  due  to  heterophoria. 

Of  course  the  symptoms  of  muscular  asthenopia 
depend  upon  binocular  vision,  and  the  man  who  ex- 
pects to  cure  strain  in  one  eye  by  tiring  them  both 
would  hardly  be  expected  to  meet  with  success ;  yet 
I  frequently  find  a  patient  with  a  plane  or  nearly 
plane  glass  over  one  eye  and  a  strong  lens  over  the 
other,  who  announces  that  the  oculist  who  gave  these 
glasses  found  that  one  eye  was  doing  all  the  work, 
and  corrected  the  other  with  a  glass  so  that  it  might 
relieve  the  strain  from  which  the  first  one  was  suffer- 
ing. Many  men  have  gone  through  the  phase  of 
full  correction  of  each  eye,  as  their  seniors  did  not 
properly  warn  them,  not  caring  to  dwell  upon  that 
time  when  they  too  had  discovered  the  secret  of  the 
cure  of  all  asthenopia  with  good  vision  in  either  eye. 
A  patient  with  anisometropia  with  much  difference 
between  the  refraction  of  the  eyes  will  bear  full  cor- 
rection of  the  two  eyes  just  so  long  as  he  does  not 
use  them  together.  There  are  many  other  diffi- 
culties of  fusion  in  such  a  case  in  addition  to  the 
esophoria  in  one  lateral  direction,  the  exophoria  in 
the  opposite  one,  the  hyperphoria  on  one  side  upon 
looking  down,  on  the  other  when  looking  up,  from 
the  prismatic  action  of  one  lens  in  excess  of  the 
other;  even  if  the  patient  looks  through  the  centre 


28  Heterophorias  and  Insufficiencies. 

of  the  lens,  or  the  English  proposition  is  carried  out 
to  have  the  strength  of  the  lenses  similar  at  the 
periphery  with  a  central  paster  to  correct  the  eye 
with  greater  error,  the  unequal  antero-posterior 
shifting  of  the  nodal  points,  with  other  reasons  for 
dissimilar  retinal  images,  will  still  obtain. 

To  my  mind  the  most  satisfactory  combination 
of  eyes  for  a  life's  work  would  be  to  have  one  em- 
metropic,  the  other  myopic  about  3  D's.  In  cases  of 
anisometropia  in  which  the  difference  corresponds 
to  this,  yet  astigmatism  is  present,  it  is  well  to 
consider  the  astigmatism  alone ;  in  myopia  with  a 
difference  of  2.  or  3.  between  the  eyes  it  is  well  to 
have  a  pair  of  glasses  in  which  the  eye  with  less 
myopia  is  fully  corrected  by  a  glass  and  the  other 
lens  matches  this  or  nearly  so.  I  carry  this  idea 
so  far  as  to  occasionally  correct  in  hypermetropic 
and  presbyopic  cases  the  eye  with  the  greater  error 
for  distance,  and  with  a  glass  which  equals  this  in 
strength,  as  nearly  as  the  case  will  allow,  the  pres- 
byopia of  the  other  as  well.  It  is  absolutely  nec- 
essary to  determine  that  the  first  eye  does  not 
strain  its  accommodation  in  order  to  read  with  the 
other,  and  render  such  correction  impracticable. 

The  scope  of  this  treatise  will  not  allow  a  full  dis- 
cussion of  this  class  of  cases,  in  which  any  man  is 
liable  to  meet  with  disaster,  further  than  to  give  a 
few  additional  points  regarding  correction.  The 


A  Clinical  Study.  29 

deviation  of  the  eye  with  poorer  vision  (fortunately 
the  one  with  greater  error  in  most  instances)  is  deter- 
mined by  certain  conditions  in  the  better  eye  as 
well  as  its  own  weaknesses.  Note  in  this  connec- 
tion the  effect  upon  the  defective  eye  of  correcting 
glasses  upon  the  better  eye  in  squint  cases.  It  is  a 
matter  of  great  importance  to  find  out  in  such  cases 
just  how  strong  is  the  impulse  to  binocular  fixation 
and  the  ability  to  ignore  or  suppress  the  image  of 
one  eye;  if  the  muscular  condition  is  bad  and  the 
tendency  to  binocular  fixation  can  be  strengthened, 
it  is  justifiable  to  cultivate  the  latter  in  the  interests 
of  vision,  although  muscular  asthenopia  may  result 
which  demands  treatment. 

The  difference  in  strength  between  two  glasses  to 
which  the  eyes  may  accustom  themselves  depends 
upon  the  age  and  character  of  the  patient  and  the  con- 
dition of  the  ocular  muscles,  with  some  other  factors 
which  cannot  be  determined  clinically  at  present. 
With  one  exception,  cylinders  with  considerable 
amount  of  difference  are  borne  better  than  spheres 
with  like  differences  because  there  is  no  prismatic 
effect  in  the  direction  of  the  axis ;  differences  between 
cylinders  with  the  axes  vertical  are  better  borne  than 
in  those  with  the  axes  horizontal.  Patients  with 
strong  muscular  action,  especially  in  the  direction 
of  difference  (for  instance,  strong  sursumduction 
with  horizontal  cylinders)  bear  differences  better  than 


30  Heterophorias  and  Insufficiencies. 

those  with  weak  muscular  action ;  this  is  partly  local, 
partly  because  the  latter  condition  accompanies  neu- 
rasthenia. Sursumduction  of  i.  is  weak,  2.  ordinary, 
2.50  and  above  strong.  People  who  turn  the  head 
and  look  through  the  centres  of  their  glasses  bear 
glasses  better  than  those  who  look  at  objects  through 
or  beyond  the  edges.  Difference  of  glasses  of  2.  may 
be  well  borne  by  young  people  (under  twenty  years 
of  age),  while  I.  may  be  the  limit  past  middle  life. 
The  best  borne  differences  are  in  cylinders  with  verti- 
cal axes  as  before  mentioned,  and  the  worst  are  a 
vertical  cylinder  over  one  eye,  horizontal  over  the 
other,  in  this  case  concave  cylinders  being  worse 
borne  than  the  convex;  in  myopic  astigmatism  cyl- 
inder .5  in  each  eye,  one  vertical,  the  other  horizon- 
tal, is  usually  not  a  complete  success. 

Let  me  repeat  for  the  benefit  of  those  who  have 
had  no  trouble  so  far  in  giving  glasses  with  great 
differences,  that  almost  invariably  the  patient  in 
such  cases  suppresses  the  image  of  one  eye,  or  at 
least  does  not  have  binocular  vision.  The  only 
cases  in  which  such  a  correction  is  really  indicated 
occur  among  patients  with  no  tendency  to  asthenopia 
where  it  is  desirable  to  better  the  field  on  the  side 
of  the  defective  eye. 


CHAPTER  II. 

HYPERPHORIA. 

THE  symptoms  of  hyperphoria  differ  from  those 
of  other  forms  of  heterophoria  mostly  in  de- 
gree. The  headache  is  below  the  occiput,  or  may 
be  general  and  accompanied  by  dizziness  and  nausea ; 
it  is  pretty  constant,  although  varying  in  intensity, 
in  many  cases  perhaps  passing  away  during  a  night's 
rest  and  increasing  toward  evening,  unless  the  pa- 
tient rests  with  the  eyes  shut  during  the  day; 
occasionally  in  hyperphoria  cases  supra-orbital  or 
ciliary  pain  on  one  side  is  present,  but  it  is  doubtful 
whether  this  can  be  due  to  the  muscular  deviation 
alone.  In  this  form  of  heterophoria  congestion  of 
the  eyeball  accompanying  low  grade  conjunctivitis 
is  more  apt  to  occur  than  in  other  forms,  and  it  is 
more  likely  to  be  present  in  those  cases  occurring 
with  oblique  astigmatism ;  the  conjunctival  trouble 
is  made  worse  by  caustics  and  astringents,  and  is 
often  in  literature  grouped  with  cases  described  as 
gouty  lids,  or  in  some  instances  among  cases  of 
spring  catarrh  as  an  atypical  type  in  which  the 

31 


32  Heterophorias  and  Insufficiencies. 

anatomical  signs  of  true  Saemisch's  catarrh  are 
absent. 

The  marginal  blepharitis  which  occurs  in  some 
cases  of  increased  lacrimal  secretion  is  due  to 
irritation  from  the  discharge,  which  runs  over  the 
edges  of  the  lids  by  day,  when  they  are  open,  and 
also  at  night  because  there  is  a  predisposing  ana- 
tomical condition  in  blepharitis  cases,  consisting 
of  a  shortness  of  the  vertical  measure  of  the  lids, 
compared  to  the  horizontal  length,  which  prevents 
proper  closure  at  night.  This  fact,  which  has  been 
strangely  overlooked  by  recent  writers  on  lid  in- 
flammations, was  fully  proven  by  Fuchs  and  can  be 
verified  clinically  with  great  ease ;  the  lower  edge 
of  the  cornea  even  may  be  exposed  at  night,  and 
ulcerations  in  this  situation  may  sometimes  be  rap- 
idly cured  by  a  night  bandage,  while  resisting  other 
treatment.  It  is  by  consideration  of  the  shortened 
lids  that  we  understand  why  relapses  occur  when 
ointments  are  no  longer  applied  in  cases  of  blephari- 
tis marginalis,  and  why  correction  of  the  refraction 
or  a  muscular  defect  may  sometimes  permanently 
improve  the  condition  by  decreasing  conjunctival 
congestion  and  lacrimation. 

In  hyperphoria  hyperesthesia  retinae  and  some 
nervous  irritability  are  apt  to  be  present.  A  sign 
which  should  always  excite  suspicion  of  hyper- 
phoria is  a  tipping  of  the  head  toward  the  shoulder. 


A  Clinical  Study.  33 

The  head  is  tipped  downwards  toward  the  right 
shoulder  in  most  cases  of  left  hyperphoria  and  some 
of  right  hyperphoria;  in  other  cases  of  the  latter 
anomaly  it  is  tipped  toward  the  left  shoulder.  The 
cause  of  this  tipping  is  not  entirely  clear;  on  first 
thought  it  would  seem  as  if  it  might  occur  in  order 
to  bring  the  eye  with  the  higher  image  more  nearly 
on  a  level  with  the  other,  but  this  fails  to  explain 
all  cases.  It  should  be  remembered  that  men  are 
in  the  habit  of  tipping  the  head  toward  the  right 
shoulder  in  aiming  rifles,  and  also  in  sighting  lines 
and  objects  in  many  occupations ;  the  right  shoulder 
is  lower  than  the  left  in  right-handed  people,  and  I 
believe  that  the  sterno-mastoid  and  other  muscles  on 
the  right  side  of  the  neck  and  head  are  also  more 
powerful.  May  not  the  position  of  eyes  and  head 
be  sometimes  due  to  a  common  cause  ? 

The  right  ear  is  usually  lower  than  the  left  and 
consequently  spectacles  sag  downward  on  this  side ; 
eye-glasses  having  chains  attached  to  the  right  lens 
also  sag  in  the  same  direction.  That  vertically  de- 
centred  lenses  are  a  common  cause  of  hyperphoria 
I  have  little  doubt,  having  known  it  to  occur  from 
a  misplaced  glass,  in  cases  where  there  had  been 
orthophoria,  and  disappear  after  the  glass  had  been 
straightened  and  worn  correctly  for  a  time;  on  the 
other  hand  there  is  a  connection  in  some  cases  be 
tween  the  position  of  the  glass  and  the  hyperphoria 


34  Heterophorias  and  Insufficiencies. 

which  is  due  to  a  displacement  by  the  patient  in  or- 
der to  correct  the  deviation  and  obtain  comfort.  I  ex- 
amined at  one  time  glasses  made  by  leading  opticians 
and  found  about  one  half  with  the  optical  centre  of 
one  glass  above  that  of  the  other;  there  is  very 
much  variation  in  the  number  of  these  errors  be- 
tween different  manufacturers;  glasses  of  a  pair 
made  at  different  times,  as  when  a  broken  glass  is 
replaced,  are  more  apt  to  be  incorrect  in  this  way. 

Another  certain  cause  of  hyperphoria  is  muscular 
anomaly,  which  may  be  a  paresis  or  an  excess. 
Take  a  recent  case  in  which  I  found  right  hyperphoria 
of  5.  manifest,  2.  latent;  right  sursumduction  10., 
left  sursumduction  2.  ;  myopic  astigmatism  .5 
right  eye,  .25  left  ;  axis  of  glass  135°  and  60° 
respectively.  The  left  eye  seemed  to  lag  behind 
in  upward  movement  of  the  eyes,  and  there  was 
diplopia  in  the  left  upper  quadrant  of  the  field ;  in- 
sistent questioning  regarding  diplopia  brought  out 
the  statement  that  the  patient  thought  that  she 
remembered  seeing  double  about  three  years  ago. 
This  appears  to  be  a  case  of  paresis  of  the  left 
superior  rectus,  though  why  a  healthy  woman  of 
forty-six  years  should  have  developed  paresis  of  an 
isolated  muscle  is  a  mystery.  Investigations  upon 
injuries  to  the  eyes  during  childbirth  may  throw  light 
upon  the  etiology  of  this  class  of  cases  as  it  is  now 
doing  with  congenital  amblyopia.  Another  test  of 


A  Clinical  Study.  35 

the  muscles  of  a  woman  of  fifty-six  years  with  0.75 
D's  of  hypermetropic  astigmatism  against  the  rule  in 
one  eye,  1.50  in  the  other,  and  orthophoria,  showed 
that  divergence  varied  from  10.  to  14.,  convergence 
from  13.  to  1 6.,  right  sursumduction  was  4.,  left 
sursumduction  n.  This  seemed  to  be  a  case  of 
excess  of  the  left  superior  rectus. 

Assuming  it  to  be  evident  that  low  degrees  of 
hyperphoria  may  be  due  to  misplaced  glasses  and 
high  ones  to  muscular  defect,  I  think  I  may  add 
one  more  positive  cause  for  its  production.  I 
have  found  a  number  of  cases  with  the  right  eye 
functionally  or  optically  stronger  than  the  left,  in 
which  left  hyperphoria  first  appeared  only  upon 
convergence,  then  became  manifest  with  fixation 
lines  laterally  parallel.  This  I  believe  to  have  been 
due  to  the  fact  that  the  right  eye  not  only  con- 
verged more  strongly  than  the  left,  but  also  that  the 
depressor  muscles  of  the  cornea  were  stronger;  that 
it  tended  to  go  below  the  left  first  upon  convergence, 
then  permanently;  I  am  sure  this  is  the  mechanism 
in  some  cases  of  convergent  squint  with  sursum- 
vergens,  and  although  the  squinting  eye  deviates 
upward  it  is  really  because  the  other  went  below  it 
in  the  first  instance. 

The  other  causes  now  to  be  given  to  account  for 
hyperphoria  I  consider  rather  speculative.  The  first 
is  that  when  eyes  are  on  a  different  level  the  muscles 


36  Hcterophorias  and  Insufficiencies. 

become  abnormal  by  attempting  to  bring  the  visual 
lines  on  a  horizontal  plane;  this  may  be  an  occa- 
sional cause,  as  the  two  conditions  coexist;  yet  if 
there  is  orthophoria,  hyperphoria  is  not  caused  by 
tipping  the  head,  in  the  few  cases  that  I  have  studied 
in  order  to  note  the  effect  of  difference  in  level  of 
the  eyes  upon  the  ocular  muscles,  which  brings  us 
to  the  connection  between  hyperphoria  and  wry  neck. 
In  hyperphoria  the  head  is  inclined  to  the  side 
with  a  twist,  the  base  line  (between  the  centres  of 
rotation)  sharing  in  the  inclination ;  in  the  limited 
observations  of  spasmodic  wry  neck  I  have  made, 
there  was  a  more  or  less  successful  attempt  to  adjust 
the  eyes  (having  no  hyperphoria)  by  bringing  them 
up  on  a  horizontal  line  by  giving  a  compensatory 
twist  of  the  head  away  from  that  of  the  neck. 

The  head  tipping  in  hyperphoria  causes  lateral 
curvature  of  the  spine;  the  mechanism  is  perfectly 
apparent ;  I  have  seen  such  cases,  and  I  think  they 
occur  somewhat  frequently.  The  present  methods 
of  keeping  a  child's  head  straight  in  school  work, 
and  the  introduction  of  vertical  script  do  not  meet 
the  conditions  in  hyperphoria  any  more  than  in  cer- 
tain cases  of  astigmatism,  and  may  in  some  instances 
result  in  the  very  troubles  they  are  intended  to 
prevent. 

The  next  speculative  consideration  in  the  produc- 
tion of  hyperphoria  is  optical.  That  anomalies  of 


A  Clinical  Study.  37 

the  elevator  and  depressor  muscles  of  the  eyes  may 
change  the  axis  of  astigmatism  by  a  rotary  action  of 
the  cornea  in  some  instances  may  be  true,  but  that 
does  not  account  for  the  production  of  the  hyper- 
phoria.  I  have  looked  over  one  thousand  cases 
tested  for  refractive  and  muscular  errors  in  the  last 
three  years  and  find  465  (46.5  %)  with  oblique  astig- 
matism;  all  other  refractive  errors  535  (53.5  $).  By 
oblique  astigmatism  I  mean  with  the  axis  not  ex- 
actly vertical  or  horizontal,  and  the  above  proportion 
is  about  what  I  have  found  in  my  cases  for  many 
years.  If  the  cylinder  gives  no  better  vision  at  an 
oblique  axis  than  when  straight,  or  than  a  spherical, 
the  case  is  not  counted  as  oblique  astigmatism. 
Hyperphoria  occurred  in  20.8%  of  all  cases;  in  the 
oblique  astigmatic  cases  26.6$,  in  the  others  14$. 
Hence  there  is  evidently  a  connection  between  an 
oblique  axis  of  astigmatism  and  the  production  of 
hyperphoria.  There  were  nearly  double  the  number 
of  hyperphorias  in  women  that  there  were  in  men, 
but  as  the  proportion  of  women  to  men  was  not 
much  less  than  that,  the  percentage  may  be  con- 
sidered nearly  equal.  In  women  right  hyperphoria 
occurred  in  general  more  often  than  left  by  about 
20%.  In  oblique  astigmatism  it  was  rather  more  fre- 
quent by  comparison  than  in  other  cases.  In  men 
left  hyperphoria  was  more  than  twice  as  frequent  as 
right,  in  refractive  errors  other  than  oblique  astig- 


38  Heterophorias  and  Insufficiencies. 

matism  the  proportion  being  more  than  2.5  to  i. 
The  explanation  of  the  more  frequent  occurrence  of 
left  hyperphoria  in  men  has  been  already  touched 
upon.  Men  are  more  right  eyed  because  of  their 
habits  and  training  than  women  (about  half  of  whom 
are  so  binocular  that  they  cannot  wink),  and  have 
more  tendency  to  depress  the  right  eye.  If  men 
and  women  with  better  vision  in  the  left  eye,  and 
women  with  equal  vision  in  the  two  eyes  are  elimi- 
nated, the  proportion  of  left  hyperphoria  to  right 
perceptibly  rises;  this  is  even  more  apparent  if  left- 
handed  persons,  who  use  the  left  eye  in  shooting, 
are  also  left  out  of  the  count.  It  is  perfectly  evi- 
dent from  a  study  of  these  cases  of  hyperphoria, 
leaving  out  the  purely  muscular  cases,  which  may  or 
may  not  cause  torsion  of  the  vertical  meridian,  that 
there  is  a  class  of  cases  caused  by  oblique  astig- 
matism. There  are  three  ways  in  which  this  may 
be  explained;  first  by  inco-ordination  of  muscular 
action ;  second,  by  an  attempt  on  the  part  of  the 
rotating  muscles  to  change  the  axis  to  a  better  po- 
sition; this  latter  explanation  seems  plausible  until 
it  is  applied  to  the  cases  singly,  when  it  is  seen  to 
be  inapplicable  to  many.  Some  of  these  hyper- 
phorias  disappear  with  the  proper  correcting  glasses, 
and  the  disappearance  is  not  always  due  to  pris- 
matic action,  although  this  is  hard  to  eliminate; 
a  third  way  to  explain  the  combination  we  are 


A  Clinical  Study.  39 

considering  is  to  suppose  that  in  some  of  these  cases 
the  muscles  are  normal,  but  the  vertical  deflection  of 
light  caused  by  difference  in  the  height  of  the 
corneal  centres  gives  the  vertical  displacement 
shown  by  the  test,  which  is  optical,  not  muscular. 
This  idea  has  a  practical  side,  which  is  that  oblique 
cylinders  can  be  sometimes  adjusted  so  as  to  cause 
hyperphoria  to  disappear,  and  that  accuracy  in  find- 
ing exactly  the  proper  axis  of  a  correcting  cylinder 
is  an  important  consideration. 

Latent  muscular  trouble  is  like  latent  hyperme- 
tropia.  It  is  that  portion  of  the  ocular  error  which 
the  observer  fails  to  find ;  what  is  latent  at  one  time 
to  one  man  is  manifest  to  another  under  other  con- 
ditions. When  the  amount  of  hyperphoria  equals 
the  difference  between  right  and  left  sursumduction 
it  is  usually  all  manifest ;  when  hyperphoria  is  less 
than  this  difference,  there  is  probably  some  of  it 
latent,  which  is  likely  to  become  manifest  later. 
This  sounds  correct,  and  has  proven  so  to  my  mind, 
but  it  presupposes  a  diagnosis  of  hyperphoria,  which 
is  not  always  easy  to  make.  It  is  my  purpose  to 
present  as  nearly  as  possible  a  composite  picture 
of  the  more  frequent  and  ordinary  weaknesses  of 
muscular  action,  since  neither  the  writer  nor  reader 
could  stand  a  detailed  statistical  description  of  some 
thousand  cases ;  an  occasional  history  to  emphasize 
the  rule  by  showing  the  exception,  or  to  illustrate 


4O  Heterophorias  and  Insufficiencies. 

the  occurrence  of  what  is  frequently  denied  to  exist, 
seems  to  be  indicated.  I  used  to  share  in  the  sneers 
of  my  medical  friends  regarding  latent  hyperphoria 
even  after  being  convinced  of  the  frequency  and  im- 
portance of  the  trouble  itself.  In  June,  1892,  a  boy 
of  thirteen  years  who  had  been  under  the  care  of  a 
careful  and  competent  ophthalmologist  and  fitted  by 
him  two  years  before  with  sph.  —  .5  O  cyl-  — -5 
changed  to  me  as  a  matter  of  convenience.  Under 
atropine  I  found  myopia  of  2.50  with  myopic  astig- 
matism of  i.  in  addition,  vision  =  f$;  there  was  or- 
thophoria  with  prism  convergence  at  20  feet  of  16., 
divergence  7.  A  diagnosis  of  slowly  progressing  my- 
opia with  congestion  of  the  choroidal  and  conjuncti- 
val  vessels  was  made  and  some  asthenopia  which  was 
present  seemed  natural  under  the  circumstances. 
Although  the  myopia  and  astigmatism  increased 
only  about  1.50  in  the  next  two  years,  still  the  cho- 
roidal condition  in  connection  with  it  was  held  to 
fully  account  for  the  increasing  hyperesthesia  of 
the  retina,  and  with  changes  in  the  nasal  mucous 
membrane  for  the  lacrimation  and  recurrent  attacks 
of  follicular  conjunctivitis,  which  latter  came  on 
several  times  in  the  two  years  and  were  apparently 
successfully  combated  with  astringents,  although 
treatment  of  the  nose  was  instituted  during  one 
attack  before  it  began  to  yield.  Vision  by  this  time 
hovered  about  f$,  being  usually  rather  below  this, 


A  Clinical  Study.  41 

and  the  headaches  and  eye  weakness  had  increased 
so  that  the  boy  was  kept  out  of  school  and  not  per- 
mitted to  go  into  business.  Twenty-seven  months 
after  I  first  saw  him  he  came  into  my  office  suffering 
from  an  exacerbation  of  his  trouble,  which  was  by 
now  pretty  constant  as  regarded  lacrimation  and 
severe  headache,  and  as  he  attempted  to  look  at  me 
with  his  congested  eyeballs  some  sort  of  a  chemical 
change  occurred  in  my  memory  cells  which  insisted 
to  me  that  there  must  be  hyperphoria  here.  A  test 
with  the  Maddox  rod  showed  i^°  (old  style)  of  right 
hyperphoria,  which  is  usually  more  potent  for  mis- 
chief than  left  hyperphoria.  A  little  coaxing 
brought  out  2°  the  next  day,  and  prisms  of  .75  were 
ordered  in  each  eye,  base  down  right  eye,  base  up 
left,  with  the  sphere-cylinders  as  before.  The  re- 
sult was  cessation  of  headache  and  decreased 
conjunctival  congestion  and  lacrimation  almost  im- 
mediately ;  the  patient  read  f $  -f-  with  either  eye 
one  week  later  and  went  into  business;  had  one 
headache  in  a  year,  but  found  that  he  had  fever  at 
the  same  time  and  went  to  his  family  doctor.  In 
eighteen  months  all  elements  in  the  glass  were 
slightly  increased  in  strength,  the  prism  now  being 
i.  o.  u.  Two  and  a  half  years  after  this,  Septem- 
ber, 1898,  the  eyes  began  to  be  uncomfortable  again, 
and  examination  showed  V.  =  f$  with  sphero-cylin- 
ders  slightly  increased  in  strength,  right  hyperphoria 


42  Heterophorias  and  Insufficiencies. 

3.50.  In  the  glass  ordered  prisms  were  increased  to 
1.50  each  and  the  patient  told  that  should  his  head- 
ache return  after  a  time  an  operation  would  be  indi- 
cated, as  stronger  prisms  would  not  do  as  well  as  the 
others.  I  have  heard  of  the  patient  once  lately 
and  he  was  reported  comfortable.  This  is  a  case  of 
hyperphoria  which  had  been  latent  to  me;  to  some 
men  all  hyperphoria  is  latent. 

There  is  some  interest  taken  in  the  usual  course 
of  hyperphoria ;  it  shares  with  some  other  things  a 
tendency  to  appear  or  disappear,  increase  or  de- 
crease or  remain  stationary.  It  usually  increases, 
and  I  doubt  whether  the  high  amounts  ever  disap- 
pear without  operation,  unless  they  are  caused  by 
transient  paresis  of  an  ocular  muscle. 

Hyperphoria  of  .25  should,  I  think,  be  ignored, 
and  I  wish  I  could  say  the  same  of  hyperphoria  of 
.50,  but  this  causes  occasionally  some  trouble,  de- 
pending upon  the  sensitiveness  of  the  patient  and 
weakness  of  sursumduction ;  thus,  if  sursumduction 
shows  respectively  I.  and  1.50,  a  deviation  of  .50  is 
apt  to  cause  discomfort.  Larger  amounts  are  potent 
sources  of  mischief  until  among  the  higher  grades 
some  of  them  become  strabismus  sursumvergens  and 
muscular  asthenopia  becomes  improbable.  It  is  well 
to  correct  the  manifest  hyperphoria  entirely  with 
prisms,  or  only  leave  .25  or  .50  uncorrected,  up  to  an 
amount  of  2  Ds.  From  2.50  to  3.50  or  above  from 


A  Clinical  Study.  43 

three  fourths  down  to  two  thirds  may  be  corrected. 
In  hyperphoria  of  3.  and  upwards  it  is  better  in  gene- 
ral to  operate,  but  it  is  often  convenient  to  try  prisms 
in  order  to  note  the  effect  and  convince  the  patient 
of  the  necessity  for  operation  when  more  hyper- 
phoria becomes  manifest,  as  it  is  likely  to  do  in  a 
year,  more  or  less.  If  manifest  hyperphoria  of  i. 
or  less  is  to  be  corrected,  I  order  the  prism  over  the 
eye  with  poorer  vision,  and  in  cases  with  equal 
vision  over  the  left.  This  leaves  a  chance  to  change 
only  one  glass  when  increased  prismatic  correction 
is  indicated  at  a  later  time.  Correction  of  1.50  or 
over  it  is  well  to  distribute  between  the  eyes,  base 
down  over  one,  base  up  over  the  other,  unless  the 
deviation  is  decidedly  limited  to  one  eye.  Other 
indications  for  varying  the  position  of  the  prisms 
are  limitation  of  upward  or  downward  movements, 
use  to  be  made  of  the  glass,  and  other  minor 
considerations.  Take  for  instance  the  common 
condition  of  left  hyperphoria  with  I.  of  hyperphoria 
with  the  rod  over  the  right  eye,  1.5  when  it  is  over 
the  left  eye.  In  this  case  the  right  eye  is  more  used 
to  fixing,  and  were  it  a  case  of  squint  the  left  eye 
would  deviate.  A  prism  of  I.  base  up  right  eye  in 
such  a  case  would  be  likely  to  cause  more  difficulty 
when  first  worn  than  one  of  1.50  base  down  left  eye, 
for  obvious  reasons. 

It  is  easy  to  demonstrate  the  necessity  of  vertical 


44  Heterophorias  and  Insufficiencies. 

prisms  in  many  cases;  if  the  prism  correcting  the 
hyperphoria  is  placed  over  one  of  the  glasses  correct- 
ing the  refraction,  then  reversed,  most  patients  can 
tell  which  direction  is  comfortable  and  which  dis- 
tressing without  any  hypnotic  suggestion. 

It  is  usually  presupposed  that  there  is  an  error  of 
refraction  to  correct  in  considering  the  ordering  of 
prisms.  If  no  correcting  glasses  are  needed  it  would 
be  better  to  operate  in  suitable  cases,  as  many  pa- 
tients cannot  be  depended  upon  to  wear  glasses 
which  do  not  help  vision,  even  when  symptoms  are 
relieved  by  them.  I  have  seen  simple  vertical 
prisms  dropped  in  a  case  of  hyperphoria  because  the 
headache  was  better;  two  years  later  the  child  af- 
fected was  under  treatment  for  lateral  curvature  of 
the  spine.  The  headache  returned  after  a  time  but 
the  glasses  seemed  if  anything  to  make  it  worse; 
inquiry  showed  that  one  prism  had  dropped  out  of 
the  frame  and  been  replaced  with  the  base  in  the 
same  direction  as  the  one  on  the  other  side.  This 
sort  of  thing  is  of  frequent  occurrence  and  produces 
curious  consequences.  A  patient  of  mine  aged 
eighty -two  had  hyperphoria  of  3.50  and  had  suffered 
all  her  life  from  severe  and  frequent  attacks  of  head- 
ache, with  nausea  and  vertigo;  measures  for  her 
relief  had  proved  futile,  the  condition  being  de- 
scribed as  "  very  bad  for  the  last  thirty  years."  I 
introduced  prisms  into  the  corrections  for  hyper- 


A  Clinical  Study.  45 

metropia  and  presbyopia  (+2.75  and  +5.,  with 
which  latter  glass  Jaeger  No.  I  could  be  read  up  to 
8"),  which  were  about  the  same  as  were  then  being 
worn.  Two  months  later  the  old  lady  reported  with 
great  delight  that  her  headaches  were  relieved. 
Three  years  later  this  patient  returned  with  evident 
senile  hebetude,  and  upon  being  asked  about  the 
headache  said  that  the  relief  had  been  only  tempo- 
rary ;  it  turned  out  that  she  had  dropped  the  glasses 
for  distance,  and  when  told  that  such  a  course  had 
caused  the  return  of  the  trouble,  was  very  positive 
that  she  did  not  need  any  distant  glasses,  as  she 
could  see  well  enough  without  them.  Spherical 
-f-6.  was  ordered  for  near  work,  with  prisms,  and 
energetic  orders  given  that  the  distant  glasses  should 
be  worn.  This  energy  was  not  thrown  away,  for 
eighteen  months  later  the  patient  again  appeared 
with  glasses  on  and  said  that  her  eyes  were  trouble- 
some still;  the  young  lady  who  now  accompanied 
her  corroborated  this  by  saying,  "  Yes,  grandma's 
eyes  are  uncomfortable,  and  she  does  not  see  well 
either."  The  old  lady  was  wearing  constantly  the 
-{-5.  formerly  given  for  near  work. 

Prisms  are  very  successful  in  relieving  asthenopia 
and  headache  when  properly  applied  in  hyperphoria 
cases,  yet  sometimes  fail  when  the  vertical  trouble 
is  secondary  to  a  lateral  deviation,  or  when  with 
vertical  and  lateral  deviations  the  latter  is  causing 


46  Heterophorias  and  Insufficiencies. 

the  symptoms.  Some  ophthalmologists  ignore  hy- 
perphoria  altogether  in  corrections,  while  others  al- 
ways correct  or  operate  upon  it  first,  knowing  the 
dire  consequences  which  sometimes  follow  the  oppo- 
site course.  It  is  safer  to  correct  the  hyperphoria 
first  in  doubtful  cases,  and  watch  the  effect  upon  the 
lateral  muscles ;  if  the  vertical  deviation  is  small  in 
amount  proportionately  to  the  lateral  and  only  occurs 
with  esophoria  or  exophoria  as  the  case  may  be,  and 
not  in  the  centre  of  the  field,  it  may  safely  be  set 
down  as  secondary.  In  a  case  of  hyperphoria  of 
this  type  with  severe  and  constant  headache,  which 
had  remained  after  careful  correction  of  the  refrac- 
tion under  atropine  and  trial  of  various  vertical 
prisms  during  a  year,  I  took  out  the  prisms,  gave 
the  less  hypermetropic  correction  without  atropine 
at  a  first  examination,  as  there  was  exophoria,  and 
the  headache  quickly  subsided  unless  near  work  was 
done,  then  after  a  time  entirely.  My  colleague  of 
a  neighboring  city,  who  had  been  so  carefully  study- 
ing and  treating  the  case  before  he  came  very  prop- 
erly to  the  question  of  operation,  would  be  a  little 
surprised,  perhaps,  if  he  knew  how  easily  relief  was 
obtained. 

In  considering  the  relative  importance  of  the  ver- 
tical and  lateral  deviations  it  may  sometimes  be  ad- 
visable to  order  an  oblique  prism.  I  have  this  day 
seen  a  patient  who  was  wearing  a  prism  base  out 


A  Clinical  Study.  47 

over  one  eye,  base  up  over  the  other.  An  easy  way 
to  figure  an  oblique  prism  is  to  take  some  unit  of 
measure  (as  a  centimetre)  and  draw  a  vertical  line 
with  the  same  number  of  units  as  the  number  which 
marks  the  strength  of  the  prism  desired  to  correct 
the  hyperphoria.  At  the  end  of  this  line  another 
at  right  angles  is  drawn  with  the  number  of  units 
corresponding  to  the  horizontal  prism  desired,  then  a 
parallelogram  constructed.  Keeping  the  direction 
of  the  prisms  in  mind,  a  diagonal  line  is  now  drawn 
from  the  corner  where  the  apices  would  meet  to  that 
between  the  bases,  which  in  the  units  of  measure 
will  show  the  strength  of  the  oblique  prism,  and  by 
its  direction  the  axis.  This  oblique  prism  is  the 
exact  equivalent  of  the  combination  of  the  two 
others. 

In  operating  for  hyperphoria,  tenotomy  of  the 
stronger  superior  rectus  is  usually  done,  for  what 
seem  to  the  writers  upon  the  subject  good  and  suffi- 
cient reasons.  I  have  not  as  yet  had  to  advance  an 
inferior  rectus  except  in  cases  of  strabismus.  In 
order  to  do  the  operation  the  eye  is  rendered  super- 
ficially insensible  to  pain  by  cocaine  or  holocaine. 
I  use  the  latter  because  it  penetrates  more  deeply 
and  has  no  effect  on  the  circulation  and  pupil. 
There  is  apparently  less  secondary  subconjunctival 
hemorrhage  and  oedema  than  from  cocaine,  but  I 
have  seen  many  more  attacks  of  faintness  following 


48  Heterophorias  and  Insufficiencies. 

its  use  than  I  ever  saw  after  cocaine,  so  I  incline  to 
think  it  more  toxic  and  have  whiskey  close  by  when 
I  use  it.  After  the  eye  is  flushed  with  neutral  salt 
solution  the  upper  lid  is  supported  by  the  ring  finger 
of  the  left  hand,  which  holds  a  pair  of  fine-pointed 
forceps  between  the  forefinger  and  thumb.  The  little 
finger  is  understudy  for  the  ring  finger,  the  middle 
finger  goes  with  the  forefinger.  As  the  eyeball  is 
directed  downwards  the  conjunctiva  is  grasped  over 
the  middle  of  the  insertion  of  the  superior  rectus 
muscle,  and  with  the  tenotomy  scissors  in  the  right 
hand  a  cut  is  made.  Through  this  the  centre  of  the 
muscle  tendon  is  grasped  by  the  forceps  and  cut ; 
from  this  laterally  cuts  are  made,  with  the  tendon 
grasped  between  the  blades  of  the  scissors,  until 
orthophoria  is  obtained,  the  eyes  being  tested  after 
each  cut.  A  bandage  should  be  worn,  for  comfort 
and  to  control  hemorrhage,  but  a  few  hours;  if  the 
patient  then  uses  the  eyes  the  full  effect  of  the 
operation  may  remain,  or  may  be  kept  by  forcing 
downward  motion.  The  deviation  may  partly  re- 
turn, one  third  of  the  original  being  the  most  I  have 
as  yet  seen  come  back,  but  allowance  cannot  be 
made  for  this  without  risk  of  over-correction.  In 
this  tenotomy  there  is  usually  a  scarlet-looking  eye 
by  the  second  day,  as  the  blood  under  the  conjunc- 
tiva settles  downwards  on  both  sides  over  the  sclera ; 
the  main  trouble  I  have  experienced  from  this 


A  Clinical  Study.  49 

operation  has  been  annoyance  from  the  complaints 
concerning  the  red  eye  from  patients  and  their 
friends.  The  fine-bladed  scissors  of  Stevens  I  have 
had  to  give  up  after  trials  of  several  pairs;  they 
tangle  up  in  the  muscle  fibres  and  do  not  cut  cleanly 
through  them  when  the  muscle  is  well  developed, 
and  considerable  effect  is  desired,  as  in  most  cases 
upon  which  I  operate. 


CHAPTER   III. 

ESOPHORIA. 

DESCRIPTIONS  of  that  type  ot  headache 
called  migraine  all  need  to  be  remodelled 
from  the  standpoint  of  recent  knowledge  of  eye 
strain,  and  especially  with  reference  to  the  type  of 
headache  occurring  from  esophoria.  The  only 
headaches  of  the  "  sick  headache  "  type  which  are 
extremely  unlikely  to  occur  from  esophoria  are  those 
in  which  gastric  or  intestinal  disturbances  of  a  marked 
type  precede  the  headache,  and  this  occurs  in  the 
form  of  very  severe  hemicrania ;  in  this  type  of  head- 
ache there  is  sometimes  a  suspicion  of  some  station- 
ary and  chronic  change  in  the  bones  of  the  skull, 
causing  pressure  or  irritation  of  the  brain,  its  mem- 
branes, or  its  blood-vessels,  in  which  case  paresis  of 
an  external  rectus  muscle  may  occur  with  the  head- 
ache attacks.  Possibly  spasm  of  convergence  may 
occur  from  irritation  of  the  convergence  centre  in 
migraine  cases,  but  it  is  rare.  A  good  illustration 
of  a  form  of  sick  headache  not  due  to  ocular  anomaly 
may  be  found  in  cases  of  arterio-sclerosis ;  these 

50 


A  Clinical  Study.  5 1 

latter  headaches  increase  with  age  and  are  to  be 
differentiated  not  so  much  from  the  headaches  of 
esophoria  as  from  those  of  exophoria. 

The  regular  history  of  the  headache  of  esophoria, 
which  is  uncomplicated  by  other  forms  of  eye  error, 
is  that  it  is  periodic,  and  accompanied  by  dizziness 
and  nausea.  Its  occurrence  may  be  usually  traced 
to  prolonged  use  of  the  eyes  in  distant  vision ;  thus 
it  occurs  after  attendance  at  a  theatre  and  is  apt  to 
be  referred  to  the  close  air ;  after  shooting  at  a  rifle 
range,  when  it  is  supposed  to  be  due  to  exposure  to 
draughts  of  fresh  air;  after  a  course  of  art  study  or 
the  like,  when  it  is  known  to  come  from  lack  of  exer- 
cise ;  after  bicycle  rides,  when  it  is  considered  evident 
that  it  is  due  to  too  much  exercise.  During  or 
preceding  the  attacks  the  latent  esophoria  is  apt  to 
become  manifest,  and  in  some  cases,  whether  mus- 
cular or  accommodative,  homonymous  diplopia  may 
result.  In  most  cases  of  headache  from  esophoria 
the  trouble  tends  to  diminish  toward  middle  age  as 
the  interni  become  weaker  and  the  refractive  error 
becomes  manifest ;  and  this  result  is  referred  to  all 
sorts  of  causes  except  the  real  one,  which  is  spon- 
taneous improvement  or  disappearance  of  the 
esophoria. 

It  must  be  kept  in  mind  in  all  cases  of  heterophoria 
that  there  may  be  no  symptoms  at  all  (in  which  case 
the  deviation  requires  no  treatment,)  or  all  of  the 


5  2  Heterophorias  and  Insufficiencies. 

usual  symptoms,  or  any  combination  of  them.  It 
has  happened  to  me  to  observe  much  dizziness,  with 
or  without  nausea,  from  esophoria,  and  more  cases 
of  vertigo  in  this  than  other  heterophorias;  in  fact 
this  and  hyperphoria  have  so  far  furnished  the  few 
cases  of  vertigo  with  falling  that  I  have  seen  relieved 
by  eye  treatment. 

Accommodative  Esophoria.  Esophoria  with  Hy- 
permetropia. —  Esophoria  is  usually  accommodative 
and  due  to  spasm  of  convergence,  accompanying 
spasm  of  accommodation,  in  uncorrected  hyper- 
metropia.  When  i.  or  less  it  may  be  ignored  ex- 
cept in  cases  of  neurasthenic  muscular  asthenopia 
with  weak  action  of  the  interni  and  externi ;  in  rare 
cases  esophoria  of  i.  or  less  may  be  due  to  false  pro- 
jection, the  eyes  converging  for  20  feet  and  the 
mind  projecting  the  images  to  infinity.  In  many 
cases  of  accommodative  esophoria  in  young  people 
the  case  may  be  diagnosed  with  ease.  Divergence 
is  not  below  normal,  and  when  a  proper  correction 
for  hypermetropia  is  put  upon  the  eyes  orthophoria 
or  even  exophoria  and  excess  of  divergence  may  im- 
mediately result,  or  develop  after  the  glass  correction 
has  been  worn  for  some  time. 

In  view  of  the  peculiar  expression  some  ophthal- 
mologists have  at  the  mention  of  esophoria  with  in- 
sufficiency of  the  interni  or  excess  of  the  externi, 
as  well  as  the  peculiar  statements  in  some  quarters 


A  Clinical  Study.  53 

about  the  lack  of  effect  upon  convergence  through 
the  accommodation,  let  me  present  the  case  of  a  lad 
who  came  into  my  office  a  few  days  ago  and  saved 
me  the  trouble  of  deciding  which  of  the  many  cases 
among  the  histories  of  such  should  be  described,  as 
I  do  not  expect  any  other  to  present  a  more  marked 
example  of  divergence  excess  and  esophoria.  The 
boy's  age  is  sixteen,  and  +2.75  spherical  is  being 
worn.  There  is  -|~4-5O  of  hypermetropia,  and  .50 
of  astigmatism  in  addition,  with  better  accommoda- 
tion in  the  right  eye  than  the  left.  V.  =  f$,  R.  E., 
f$,  L.  E.  At  20  feet  there  is  an  esophoria  of  4.5, 
convergence  20.,  with  forcing  after  instruction  and 
practice  35.,  a  little  left  hyperphoria  with  conver- 
gence. Divergence  15.  The  convergence  near  point 
is  5  inches,  at  which  distance  the  eyes  begin  to 
diverge,  although  by  an  effort  fixation  can  be  recov- 
ered and  the  eyes  forced  to  converge  nearer.  Exo- 
phoria  at  13",  4  D's.  With  full  correction  of  the 
refraction  there  is  orthophoria,  divergence  still  15., 
convergence  not  so  good  as  without  the  glass.  If  I 
may  judge  by  experience  these  eyes  will  have  exo- 
phoria  before  long,  and  perhaps  divergent  squint 
later,  although  without  proper  correction  of  the  re- 
fraction there  is  now  periodic  convergent  squint 
which  the  patient  has  observed.  These  cases  should 
be  treated  for  the  accommodative  esophoria  first  by 
correcting  the  refraction,  later  for  the  exophoria  and 


54  Heterophorias  and  Insufficiencies. 

excess  of  the  extern!  by  tenotomy  of  the  latter 
muscles;  always  provided  there  is  muscular  asthe- 
nopia  or  the  condition  is  passing  into  strabismus. 

The  diagnosis  of  accommodative  esophoria  is  not 
always  easy.  As  time  goes  on  in  these  cases,  if  the 
refraction  is  not  corrected,  divergence  becomes 
weaker  and  may  be  as  little  as  5.,  seldom  lower.  It 
may  well  be  asked  why  divergence  of  less  than  5. 
should  be  arbitrarily  given  as  not  belonging  to  ac- 
commodative esophoria  when  it  is  well  known  that 
convergent  squint  is  often  if  not  usually  of  accom- 
modative origin.  It  seems  to  me  that  in  cases 
where  the  desire  for  binocular  fixation  is  so  strong 
that  it  will  allow  esophoria  only  to  result,  and  where 
the  spasm  of  accommodation  and  convergence  ex- 
cept for  this  desire  would  cause  squint,  the  externi 
would  hardly  fall  below  a  standard  of  power  suffi- 
cient to  insure  binocular  fixation,  with  a  margin  left 
for  emergencies,  unless  they  were  insufficient ;  for 
practical  purposes,  divergence  of  4.  or  less  should  be 
considered  as  a  muscular  insufficiency,  unless  conver- 
gence is  also  correspondingly  weak,  when  the  case 
belongs  to  another  class  to  be  considered  later. 

All  cases  of  esophoria  with  headache,  dizziness,  or 
nausea  after  use  of  the  eyes  for  distant  vision,  in 
which  the  muscular  deviation  does  not  yield  to  cor- 
rection of  the  manifest  hypermetropia,  should  (un- 
less surely  myopic)  be  put  under  atropine.  In 


A  Clinical  Study.  55 

certain  young  persons,  with  a  moderate  amount  of 
hypermetropia  and  spasm  of  accommodation  which 
entirely  conceals  the  refractive  error,  there  is  eso- 
phoria  with  periodic  headaches,  accompanied  by 
dizziness  and  nausea,  which  are  relieved  by  correct- 
ing the  refraction  as  shown  under  atropine  less  .25 
or  .50;  after  a  time  the  esophoria  disappears  entirely 
and  the  glass  is  dropped  without  a  return  of  the 
symptoms.  A  certain  amount  of  the  hypermetropia 
I  consider  the  artificial  production  of  the  atropine ; 
some  patients  may  bear  the  full  correction  found 
under  atropine,  but  more  do  not;  if  a  correction  is 
given  which  does  not  allow  of  clear  distant  vision 
after  the  atropine  is  no  longer  used,  the  patient, 
especially  if  still  in  the  years  of  childhood,  is  likely 
to  look  over  the  glasses  for  distant  vision  and  thus 
defeat  the  desired  effect  upon  the  muscles  through 
the  accommodation.  The  effect  of  accommodation 
upon  convergence  depends  upon  structural  or  edu- 
cational connection  between  the  centres  in  the  brain, 
and  is  very  variable  in  different  people. 

It  may  be  of  interest  to  know  the  slow  mental 
processes  by  which  the  writer  arrived  at  some  of  these 
conclusions  which  he  has  set  forth.  Under  an  able 
and  thorough  chief,  during  some  years  I  tested  the 
refraction  of  several  thousand  patients  under  atro- 
pine; as  time  went  on  and  I  found  that  the  tests 
without  atropine  tallied  with  those  found  or 


56  Heterophorias  and  Insufficiencies. 

expected  under  atropine,  the  use  of  the  drug  was 
dropped.  Certain  cases  did  not  do  as  well  as  re- 
garded the  asthenopia  and  headache  as  formerly, 
when  atropine  was  used,  and  after  rinding  that  this 
resulted  when  the  glasses  were  of  no  different 
strength,  and  after  eliminating  the  question  of  rest 
to  the  ciliary  muscle  as  an  explanation,  I  found  that 
this  result  was  due  in  certain  cases  to  the  relaxation 
of  accommodative  esophoria,  and  began  to  use  atro- 
pine in  esophoria  cases  again,  as  I  had  always 
properly  been  taught  to  do  in  cases  of  convergent 
squint. 

A  few  cases  show  more  esophoria  under  atropine 
than  before  its  use.  Duane  has  explained  that  this 
is  due  to  extra  efforts  of  accommodation  induced  by 
attempts  to  contract  the  ciliary  muscle.  Reason- 
able as  is  this  explanation,  I  am  not  prepared  to 
accept  it ;  long  ago,  in  the  case  of  a  child  with  con- 
vergent squint,  in  which  atropine  increased  the  de- 
formity, the  mother  told  me  that  she  had  noticed 
increase  of  the  squint  when  her  child  was  excited 
or  agitated,  and  that  the  girl  had  been  very  angry 
about  the  drops,  the  eyes  crossing  more  just  as  soon 
as  she  knew  that  they  were  to  be  instilled.  I  have 
been  able  in  the  cases  under  discussion  to  trace  the 
result  to  spasm  of  convergence,  or  weakness  of 
divergence,  caused  by  nervous  irritability  or  ex- 
haustion; within  a  few  weeks  I  had  this  occur,  my 


A  Clinical  Study.  57 

patient,  a  neurotic  woman  of  forty,  being  in  a  very 
excited  state  because  the  atropine  had  dried  her 
throat  and  kept  her  awake;  at  the  beginning  of  the 
examination  under  atropine  esophoria  had  increased, 
but  at  the  close  when  the  patient's  excitement 
had  gone  down  the  esophoria  had  decreased  with 
it. 

Cases  of  accommodative  esophoria  may  occur  up 
to  the  age  of  fifty-five  years.  In  hypermetropic 
presbyopes  with  esophoria  spasm  of  accommodation 
may  be  suspected  when  the  glass  required  to  correct 
the  presbyopia  is  stronger  than  usual.  In  cases  of 
accommodative  or  spasmodic  esophoria  operations 
are,  of  course,  contra-indicated,  although  frequently 
performed.  It  is  in  just  this  class  of  cases  that 
tenotomy  of  the  interni  does  the  most  harm.  If  it 
is  doubtful  whether  the  case  is  accommodative  or 
muscular,  and  symptoms  are  not  relieved  by  mere 
correction  of  the  refraction,  prisms  of  just  sufficient 
strength  to  bring  divergence  up  to  the  minimum  for 
that  case  (6.  or  7.)  may  be  given.  It  may  be  some 
years  before  relaxation  of  the  interni  in  these  cases 
causes  the  esophoria  to  disappear,  but  it  usually 
occurs,  sooner  or  later. 

In  accommodative  spasm,  as  in  any  other  spasm 
(if  such  exist)  of  the  interni,  strychnine,  rest,  and 
general  tonic  treatment  often  increase  the  esophoria 
and  the  ocular  symptoms. 


5  8  Hetcrophorias  and  Insufficiencies. 

It  would  be  very  erroneous  for  any  one  to  sup- 
pose that  the  typical  symptoms  of  esophoria — head- 
ache, dizziness,  or  nausea,  with  a  tendency  to 
periodicity  occurring  after  prolonged  use  of  the 
eyes  for  distant  objects — are  usually  met  with  un- 
accompanied by  other  ocular  disturbances.  In  ac- 
commodative esophoria  especially  are  there  often 
other  disturbances  due  to  other  ocular  conditions ; 
thus  hypermetropia  and  astigmatism  may  cause 
frontal  and  temporal  headache  for  distance  and  near 
work,  and  as  in  some  other  forms  of  esophoria,  in- 
sufficiency of  the  interni,  or  of  convergence,  may 
cause  asthenopia  when  near  work  is  done,  and 
intense  and  constant  headache  may  occur  when 
esophoria  at  the  reading  distance  is  present,  which 
error  may  be  greater  than  that  for  distance. 

Esophoria  of  Habit.  Esophoria  with  Myopia. — My 
attention  was  first  attracted  to  this  class  of  cases  in 
June,  1894.  A  young  lady  of  twenty-three  years 
came  to  me  with  the  statement  that  she  saw  double 
at  times,  and  that  all  glasses  given  to  her  heretofore 
caused  much  dizziness  and  discomfort.  There  was 
myopia  of  2.25  with  a  little  astigmatism.  Eso- 
phoria of  8.  increased  to  12.  with  the  glass  (2  D.) 
now  being  worn;  convergence  25.,  divergence  5. 
At  13*  esophoria  5.,  convergence  45.,  divergence 
1 1 .  After  atropine  no  change  in  refraction ,  esophoria 
9.,  convergence  38.,  divergence  6.  There  was 


A  Clinical  Study.  59 

apparent  divergence;  especial  note  should  be  made 
of  this;  in  myopia  with  esophoria  there  is  apt  to  be 
apparent  divergence  and  the  glasses  are  often  centred 
too  broadly,  while  in  myopia  and  exophoria  there  is 
usually  apparent  convergence  and  the  opposite  error 
-ef~toe— great  an  .,o...c.  in  the  glasses  often  occurs. 
Glasses  were  ordered  in  this  case  with  prisms  1.50 
o.u.  base  out  and  o.c.  in  proper  position;  in  other 
words,  3  D's  of  prismatic  action  at  the  fixation  lines. 
These  glasses  caused  no  discomfort  from  the  first, 
but  three  months  later  the  patient  asked  if  she  could 
not  have  a  less  clumsy  glass,  as  the  thick  outer  edges 
of  the  present  one  attracted  attention.  Esophoria 
was  now  6.  This  was  accomplished  by  making  the 
p.d.  narrower,  the  centre  of  glasses  being  3  mm. 
inside  the  lines  of  fixation,  and  no  prism  ordered. 
Three  weeks  after  this  the  left  eye  having  a  little 
neuralgic  pain  when  the  glass  was  worn,  esophoria 
was  found  to  be  down  to  2.  without  any  glass,  and 
also  with  the  last  glass.  The  discomfort  subsided 
shortly  after,  and  the  patient  brought  in  her  mother, 
who  had  high  myopia  and  convergent  squint,  the 
eyes  converging  for  the  far  point  of  accommodation, 
which  was  2^"  from  the  root  of  the  nose,  and  not 
diverging  for  distant  objects.  Convergent  squint 
with  myopia  had  before  this  excited  my  interest, 
and  after  concluding  that  it  resulted  from  the  habit 
of  fixing  near  objects,  I  found  that  this  explanation 


60  Heterophorias  and  Insufficiencies. 

and  no  other  had  been  given  by  all  writers  who  had 
considered  its  causation. 

After  this  esophoria  and  myopia  attracted  my  at- 
tention, and  soon  after  I  had  an  opportunity  to 
treat  two  sisters  with  this  combination;  one  had 
already  had  twelve  operations  done  in  the  vain  en- 
deavor to  straighten  the  eyes,  the  only  result  having 
been  much  fatigue  to  the  nervous  system ;  the  other 
had  long  been  troubled  with  dizziness  and  had  been 
treated  for  "  the  liver  "  without  relief  to  that  symp- 
tom. In  the  latter  case,  as  the  decentred  lenses 
ordered  seemed  to  cause  asthenopia,  I  ordered  prisms 
for  the  same  muscular  effect  (combined  with  the 
correction  for  the  refraction,  practically  the  same 
that  was  being  worn  before  I  saw  the  case),  and  the 
dizziness  subsided  slowly,  disappearing  within  a 
month.  It  returned  about  three  years  later,  when 
it  was  found  that  orthophoria  was  present  instead 
of  esophoria  of  3.,  and  the  prisms  of  I.  base  out  were 
taken  from  the  glasses,  when  the  dizziness  and 
asthenopia  again  disappeared.  In  the  case  of  the 
first  sister  there  was  esophoria  of  /.,  right  hyper- 
phoria  of  i.,  and  it  is  not  necessary  to  narrate  the 
details  of  the  glasses  decentred  inwards,  and  the 
good  effects,  except  to  say  that  in  three  years 
the  hyperphoria  disappeared,  as  it  was  a  converg- 
ence hyperphoria,  and  esophoria  was  I.  instead  of 
7.  The  father  of  these  girls  has  hypermetropic 


A  Clinical  Study.  61 

astigmatism  and  orthophoria,  the  mother  has  com- 
pound myopic  astigmatism  and  no  appreciable  devi- 
ation, and  another  sister  has  myopic  astigmatism, 
with  a  little  exophoria  and  excess  of  divergence. 

Since  these  cases  I  have  treated  several  scores  of 
others  with  myopia  and  the  esophoria  of  habit,  all  in 
the  same  way.  This  includes  cases  in  which  I  had 
formerly  failed  to  appreciate  the  condition.  As  a 
rule  convergence  is  not  excessive,  and  there  is  some- 
times asthenopia  for  near  work  from  insufficiency  of 
convergence;  there  is  a  fairly  definite  relation  be- 
tween the  amount  of  myopia  and  esophoria;  I  de- 
centre  the  glasses  from  2  to  4  mm.,  so  that  there 
is  prismatic  action  at  a  distance  with  the  prisms  base 
out,  and  usually  some  prismatic  action  in  the  oppo- 
site direction  for  reading  distance.  This  is  not  done 
at  haphazard  ;  the  object  is  to  get  the  least  prismatic 
action  that  will  cause  comfort  to  the  patient,  in  the 
expectation  that  improvement  or  cure  of  the  devia- 
tion will  result  as  the  eyes  become  accustomed  to 
fixing  at  a  distance.  The  trouble  occurs  in  persons 
who  have  gone  with  their  myopia  uncorrected  in 
youth ;  the  symptoms  in  some  cases  do  not  begin 
until  glasses  are  worn,  and  may  pass  off  without 
any  especial  attention  to  adjustment  of  the  lenses, 
although  not  infrequently  they  persist.  The  most 
usual  symptom  is  dizziness  with  distant  glasses, 
occasionally  headache,  and  I  have  seen  one  case  of 


62  Heterophorias  and  Insufficiencies. 

conjunctival  congestion  and  blepharitis  marginalis. 
In  this  latter  case  a  patient  whose  refraction  had 
been  corrected  returned  to  me  because  of  increas- 
ing eye  strain.  For  the  esophoria,  which  had  pre- 
viously been  ignored,  appropriately  centred  glasses 
were  ordered.  I  had  no  chance  to  verify  the  cor- 
rectness of  their  manufacture,  and  nearly  a  year 
later  my  patient  returned,  complaining  that  the 
glasses  had  done  him  no  good.  The  feeling  of 
strain  and  the  lid  trouble  were  worse,  and  I  found 
that  his  optician  had  taken  the  liberty  of  correcting 
my  error  about  the  centre,  or  paid  no  attention  to 
the  directions ;  I  saw  that  the  lenses  were  decentred 
as  I  wished,  after  which  the  symptoms  promptly 
subsided,  and  the  lid  congestion  as  well. 

It  will  be  noticed  that  a  distinction  was  made  in 
two  of  these  cases  between  prisms  and  decentred 
lenses;  I  have  given  up  any  attempt  to  keep  up 
such  a  distinction  in  clinical  work,  except  for  certain 
purposes,  as  when  I  find  it  much  easier  mentally,  as 
above  shown,  to  fit  a  decentred  lens  than  figure 
prisms,  or  when,  as  in  the  case  where  vertical  pris- 
matic action  is  desired,  I  order  prisms  instead  of 
decentred  lenses  because  I  find  this  method  easier 
as  well  as  more  likely  to  insure  correctness  in  the 
work  of  the  optician.  The  decentred  biconvex  lens 
portrayed  in  books  which  state  that  such  a  glass  is 
equivalent  to  a  prismosphere  is  dissimilar  to  the 


A  Clinical  Study.  63 

glass  ground  by  the  manufacturers  when  spheres 
and  prisms  are  ordered  in  combination,  as  the  latter 
has  one  plane  surface  and  may  be  considered  as  a 
decentred  plano-convex  or  concave  lens.  It  is  cer- 
tainly wrong  to  consider  such  lenses  as  identical, 
or  a  decentred  meniscus  as  the  exact  equivalent 
of  either  ;  the  differences  are  not  only  optical, 
but  prismatic  as  well  when  the  eyes  are  turned 
toward  the  periphery  of  the  glass,  yet  the  pain  in 
one  eye  caused  in  the  patient  above  mentioned 
when  prisms  were  replaced  by  decentred  lenses 
should  be  referred  to  the  different  position  of  the 
weak  oblique  cylinder  in  the  lens,  or  some  optical 
influence,  rather  than  difference  of  prismatic  action. 
It  is  only  by  consideration  of  such  points  that  re- 
ported cases  of  asthenopia  relieved  by  toric  lenses 
in  place  of  the  usual  kind,  or  a  change  of  frames  for 
the  glasses,  can  be  given  any  value. 

In  muscular  asthenopia  we  are  dealing  largely 
with  subjective  symptoms  caused  by  variation  in 
physiological  and  anatomical  conditions;  the  con- 
servative observer,  until  he  or  some  member  of  his 
family  suffers  from  severe  muscular  asthenopia,  is 
apt  to  remain  somewhat  skeptical  regarding  the  im- 
portance of  these  difficulties,  to  regard  a  necessarily 
artificial  classification  with  some  suspicion,  and  may 
question  the  propriety  of  the  introduction  of  a  sepa- 
rate class  for  cases  which  it  might  seem  possible  to 


64  Heterophorias  and  Insufficiencies. 

include  under  old  headings  by  means  of  some  elas- 
ticity of  distribution ;  yet  the  myopic  esophoria  of 
habit  has  strong  claims  for  recognition  as  a  clinical 
entity ;  when  it  is  recognized  and  considered  in 
glass  corrections  it  is  easily  treated  and  benefited ; 
when  not,  the  fatigue  of  the  externi  often  continues 
and  the  symptoms  may  go  on  from  bad  to  worse. 
The  esophoria  is  out  of  all  proportion  to  the  weak- 
ness of  divergence,  and  exceptionally  may  be  in- 
creased by  stimulation  to  the  accommodation  when 
concave  glasses  are  worn.  Thus  it  will  be  noticed 
in  a  test  given  above  that  esophoria  of  8.  increased 
to  12.  with  the  correcting  glass,  while  divergence  of 
6.  remained  unchanged.  It  will  also  be  noticed  that 
prism  i.  only  was  ordered  ;  I  never  order  a  prismatic 
effect  in  such  cases  which  increases  divergence  to 
more  than  8.  no  matter  what  the  esophoria.  I  fol- 
low the  same  rule  in  all  forms  of  esophoria,  but  in 
no  other  is  there  any  such  disproportion  between 
esophoria  and  divergence  after  correction  of  the 
refraction  as  in  the  esophoria  of  myopia.  It  must 
always  be  kept  in  mind  when  prisms  are  ordered 
that  the  prism  strength  is  added  to  the  muscular 
power  in  the  direction  of  the  base  and  deducted 
from  that  in  the  direction  of  the  apex. 

Passing  over  a  considerable  number  of  these  cases 
which  present  no  special  features  it  may  be  proper 
to  present  a  case  with  a  fairly  complete  history 


A  Clinical  Study.  65 

which  showed  the  deviation  and  its  effect  to  a 
marked  degree ;  in  view  of  the  astigmatic  element  in 
some  of  these  cases  it  may  be  well  to  state  that  a  con- 
siderable number  had  the  condition,  the  symptoms, 
and  the  results  without  any  astigmatism  being  found. 
A  hard-worked  financier  of  forty-eight  years  had 
been  ordered  sph.  — 9.  right  eye,  —  8.50  left,  in 
the  spring  of  1898,  by  a  careful  ophthalmologist  of 
high  standing.  He  had  signs  of  nervous  fatigue 
with  some  dyspepsia,  but  his  most  troublesome 
complaints  were  of  headache,  mostly  posterior  and 
basilar,  and  attacks  of  vertigo,  without  falling,  when 
attempts  were  made  to  look  at  distant  objects. 
His  physician,  having  found  no  relief  to  his  symp- 
toms after  a  summer's  vacation,  concluded  to  resub- 
mit  him  to  an  eye  examination,  and  I  saw  him  in 
October,  1898.  Vision  with  the  old  glasses  (62  mm, 
o.c.)  wasf$  —  o.u.  With— 9. 50  and—  9.  ^cyls.  —  i. 
and  —  .75  axis  90°  in  the  right  and  left  eyes  respec- 
tively V.  =  •§•$-  -f-  in  each.  The  eyes  without  glasses 
showed  an  indeterminate  amount  of  esophoria  and 
convergence;  divergence  I.  and  homonymous  diplo- 
pia  under  a  red  glass.  There  was  right  hyperphoria 
of  i.,  but  the  natural  sag  of  the  glass  corrected  this. 
It  was  found  that  with  the  glasses  at  56  mm.  o.c. 
orthophoria  was  at  least  temporarily  present,  and 
they  were  thus  ordered,  a  near  glass  less  the  presby- 
opic  correction  being  ordered  with  o.c.  at  60 


66  Heterophorias  and  Insufficiencies. 

as  convergence  was  weak.  This  was  done  without 
making  unnecessary  tests,  as  the  already  prolonged 
examination  had  pretty  well  exhausted  the  patient. 
The  glasses  caused  much  distress  at  first,  but  this 
wore  off,  and  the  vertigo  and  severe  headache  were 
relieved  within  a  week.  Nine  days  later  the  eyes 
with  the  glass  on  showed  for  distance  orthophoria, 
with  convergence  20.,  divergence  7.  It  is  well  to 
note  that  the  prismatic  action  of  the  glass  upon  the 
eyes  was  4.,  and  also  to  call  attention  to  the  fact 
that  the  hyperphoria  was  no  doubt  one  cause  for  the 
inco-ordinate  action  of  the  muscles  of  the  eyes  with- 
out glasses,  and  perhaps  had  a  contributing  influ- 
ence in  producing  symptoms;  as  to  the  astigmatism 
as  a  cause  of  the  vertigo  this  was  thrown  out,  since 
a  duplicate  pair  of  glasses  were  made  later  by  the 
patient's  optician  at  60  mm.  o.c.  and  they  brought 
back  the  vertigo  quickly;  another  similar  mistake 
was  made  later,  with  the  same  result.  When  the 
eyes  (or  externi)  were  fatigued,  as  after  attendance 
at  theatre,  the  esophoria  partly  returned  with  a 
feeling  of  ocular  fatigue,  and  about  2.  of  esophoria 
could  be  found  the  next  morning  (with  the  glass 
worn).  This  patient  had  clonic  blepharospasm  on 
the  left  side  and  I  treated  his  conjunctivitis  and 
blepharitis ;  when  this  failed  to  relieve  the  twitching, 
as  a  little  more  astigmatism  had  become  manifest  in 
the  left  eye,  I  ordered  a  cylinder  .25  stronger  for 


A  Clinical  Study.  67 

that  eye.  In  June,  1899,  the  patient  returned,  as 
he  had  begun  to  have  some  increasing  discomfort 
from  his  eyes,  and  he  had  been  warned  to  expect 
that  as  his  esophoria  disappeared ;  he  reported  that 
his  blepharospasm,  headache,  and  dizziness  had  re- 
mained away  after  the  last  glass  was  worn,  and  his 
ability  to  read  without  fatigue  had  gradually  im- 
proved. I  found  hyperphoria  2.  (i.  being  corrected 
by  the  glass).  With  the  glasses  on  there  was  now 
exophoria  of  2.,  divergence  of  10.  New  glasses 
were  ordered  at  60  mm.  o.c.  with  vertical  prism  I. 
(base  up,  left  eye),  and  the  patient  told  to  report  if 
not  entirely  comfortable.  This  case  is  the  only  one 
seen  by  me,  except  the  first  one  mentioned,  in  which 
periodic  squint  with  diplopia  occurred  and  the  only 
one  in  which  hyperphoria  increased  during  the  time 
the  case  was  under  observation. 

Full  correction  of  the  refraction  is  indicated  to 
give  the  best  distant  vision  and  stimulate  proper 
binocular  fixation  at  a  distance,  and  operations  are 
contraindicated  in  the  esophoria  of  habit,  which 
occurs  always,  or  nearly  always,  with  myopia. 

Muscular  Esophoria. — Esophoria  from  muscular 
causes  is  due  to  excess  of  the  interni  or  insufficiency 
of  the  externi,  and  may  occur  with  any  or  with  no 
error  of  refraction.  In  the  first  condition  conver- 
gence is  powerful,  divergence  may  be  secondarily 
omewhat  weak,  nervous  irritability  or  strychnine 


68  Heterophorias  and  Insufficiencies. 

increases  the  defect,  and  there  is  esophoria  also  for 
near  points  unless  insufficiency  of  convergence  co- 
exists. It  may  have  been  noticed  that  a  distinction 
is  made  between  insufficiency  of  the  interni  and 
externi,  and  insufficiency  of  convergence  and  diver- 
gence; by  the  first  terms  I  mean  that  there  is  a 
muscular  defect,  by  the  latter  a  deficiency,  shown 
by  the  tests,  of  an  associated  action,  which  may  be 
muscular,  nervous,  or  secondary  to  an  error  of  re- 
fraction. For  instance,  insufficiency  of  convergence 
may  be  due  to  optical,  accommodative,  or  general 
nervous  causes,  excess  of  the  externi,  fatigue,  or 
insufficiency  of  the  interni.  Whether  the  oft- 
mentioned  spasm  of  convergence  occurs  without 
excess  of  the  interni,  or  insufficiency  of  the  externi, 
except  in  general  disease,  as  meningitis,  hysteria,  or 
chorea,  or  from  local  conditions,  as  from  hyper- 
metropia,  hyperphoria,  or  improper  glasses,  is  some- 
what doubtful.  There  are  rare  cases  which  show 
good  balance  of  the  ocular  muscles  and  normal 
divergence  at  times,  which  at  others  show  esophoria 
and  weak  divergence.  Probably  these  are  mostly 
instances  of  latent  esophoria  becoming  manifest, 
like  the  other  more  numerous  cases  in  which  eso- 
phoria is  increasediunder  just  such  general  conditions. 
It  would  be  as  rational  to  refer  them  to  exhaustion 
of  divergence  as  spasm  of  convergence,  the  excess  of 
convergence  being*simply  a  secondary  result. 


A  Clinical  Study.  69 

In  cases  of  esophoria  and  excess  of  convergence 
it  is  well  to  treat  the  deviation  with  caution,  espe- 
cially when  hypermetropia  coexists,  using  atropine 
and  attempting  to  relax  the  interni ;  over-correction 
of  hypermetropia,  or  convex  glasses  for  reading  in 
non-presbyopic  cases,  I  do  not  particularly  favor, 
although  the  latter  plan  may  sometimes  be  followed 
with  benefit.  Prisms  do  well  in  the  proper  cases; 
those  in  which  the  insufficiency  of  divergence  and 
the  esophoria  practically  agree,  and  the  muscular 
condition  for  far  and  near  are  similar  and  prisms  of 
from  i.  to  2.  over  each  eye  nearly  correct  the  diffi- 
culties. In  such  cases  three  fourths  or  even  all  the 
deviation  may  be  corrected,  the  prism  being  ordered 
in  combination  with  the  glass  properly  correcting 
the  refraction.  In  cases  where  the  deviation  tends 
to  increase,  and  prisms  having  been  of  relief  are  so 
no  longer,  a  tenotomy  of  one  internus,  perhaps  fol- 
lowed by  a  tenotomy  of  the  other  later,  may  be  in- 
dicated. The  operation  is  similarly  done  to  that  for 
hyperphoria,  but  usually  needs  to  be  complete.  In 
these  operations  strength  is  sacrificed  for  position, 
convergence  is  usually  weakened  for  a  time  out  of 
proportion  to  the  good  effect  upon  the  esophoria, 
and  near  work  is  apt  to  cause  considerable  discom- 
fort for  a  week  or  two  at  least,  even  when  the  opera- 
tion was  done  delicately.  After  this  the  severe 
headache  and  symptoms  are  likely  to  be  relieved, 


70  Heterophorias  and  Insufficiencies. 

and  although  from  the  nature  of  the  anatomical 
conditions  the  esophoria  is  prone  to  return,  weeks, 
months,  or  years  later,  the  headache  and  other 
symptoms  may  not  return.  I  am  not  conscious  of 
reason  for  regret  in  having  done  this  operation  in 
the  few  cases  in  which  I  thought  it  necessary,  but  I 
have  treated  a  considerable  number  of  post-operative 
cases  after  they  had  passed  out  of  the  hands  of  col- 
leagues, and  I  am  not  highly  enthusiastic  about  the 
results. 

Most  cases  of  muscular  esophoria  are,  in  my 
opinion,  due  to  insufficiency  of  the  externi.  Strych- 
nine sometimes  will  help  the  asthenopia  in  these 
cases;  divergence  is  4.,  or  less,  and  convergence  is 
not  excessive.  The  proper  operation  is  an  advance- 
ment of  an  externus,  picking  out  the  weaker  if  this 
can  be  done,  as  is  often  possible.  The  usual  ad- 
vancement for  insufficiency  is  a  detachment  of  the 
central  part  of  the  muscle  from  its  insertion,  loosen- 
ing of  the  subconjunctival  tissue  toward  the  cornea, 
and  the  tightening  and  tying  of  a  single  horizontal 
stitch  which  is  passed  through  the  middle  of  the 
muscle  near  its  cut  end  and  the  tissue  above  the 
sclera  up  to  the  corneal  margin.  This  single  stitch 
is  entirely  effective  for  the  readvancement  of  a  teno- 
tomized  muscle  when  the  effect  is  too  great,  but  for 
cases  where  the  opposing  muscle  is  strong  I  prefer  to 
lift  the  muscle  upon  a  tenotomy  hook  after  making  a 


A  Clinical  Study.  7 1 

small  opening  above  and  below,  and  then  pass  the 
needles  at  each  end  of  a  stitch  through  this  upheld 
fold  toward  the  cornea,  grasping  conjunctiva  and 
muscle  in  a  loop  which  holds  more  than  half  the 
breadth  of  the  muscle.  The  stitch  is  tightened, 
and  tied  when  orthophoria  is  obtained ;  the  result  is 
certain  and  permanent,  and  no  bad  result  follows 
should  the  stitch  cut  through,  as  it  may  occasionally 
after  some  days.  The  operation  is  easy  and  pain- 
less, and  the  fold  in  the  muscle  disappears  gradually, 
leaving  the  effect  of  the  operation  with  no  deformity. 
Notwithstanding  the  good  points  about  this  advance- 
ment it  is  not  likely  to  come  into  general  use,  as  it 
is  not  so  picturesque  as  some  others  at  the  time 
of  and  immediately  following  the  operation.  The 
stitch  of  an  advancement  should  be  kept  in  place 
for  five  or  six  days,  the  eye  being  kept  bandaged. 
Motions  of  the  eyes  are  uncomfortable  because  of 
the  stitch,  and  are  avoided  by  the  patient  while  it 
remains  in  position,  so  I  advance,  or,  strictly  speak- 
ing, fold,  a  muscle  in  my  office,  using  no  speculum, 
and  let  my  patient  go  home  with  a  single  bandage. 
It  is  absolutely  necessary  to  test  the  eyes  at  inter- 
vals while  doing  tenotomies  and  advancements  for 
heterophoria,  and  this  cannot  be  so  well  done  if  the 
patient  does  not  sit  up  for  the  operation  in  the  office. 
I  find  confinement  in  bed  unnecessary. 

It  will  be  seen  by  the  above  that  the  old  motto 


72  Heterophorias  and  Insufficiencies. 

"  It  is  better  to  be  sure  than  sorry  "  applies  to  the 
treatment  of  esophoria.  I  am  in  no  greater  hurry 
to  operate  in  these  cases  as  time  goes  on  than  I  was 
formerly,  and  I  am  constantly  surprised  by  the  im- 
provement in,  and  disappearance  of,  certain  eso- 
phorias  without  operation  where  such  a  result  could 
hardly  have  been  predicted.  Any  centra-indication 
will  deter  me  from  operation  in  these  cases,  and  I 
will  here  mention  the  case  of  an  ophthalmologist 
who  had  suffered  severely  for  ten  years  from  extreme 
asthenopia  and  headache,  mostly  temporal  and  fron- 
tal. This  gentleman  had  consulted  colleagues  in 
various  cities  about  his  ocular  muscles  and  the  last 
one  had  proposed  to  straighten  his  physiological 
vertical  meridian,  which  tipped  a  little ;  this  last 
opinion  immediately  gave  me  a  clue,  as  I  had  seen 
such  cases  before.  The  patient  was  wearing  -\-  I. 
and  1.25  cyls.  axes  90°,  which  he  had  fitted,  and 
which  all  the  consultants  had  accepted  without  spe- 
cial investigation,  and  he  had  astigmatism  which 
was  most  perfectly  corrected  by  cyls.  -|-  1.25  and 
1.75,  axes  85°  and  100°  respectively.  There  was 
decided  vertical  insufficiency  of  the  lids,  with  con- 
junctival  congestion  and  blepharitis  marginalis.  At 
twenty  feet  esophoria  2.,  convergence  16.,  diver- 
gence 4.  At  13"  exophoria  10.  and  upwards,  from 
convergence  insufficiency ;  convergence  25.,  diver- 
gence 14.  There  was  no  hyperphoria,  and  I  told  him 


A  Clinical  Study.  73 

that  I  was  conscious  enough  of  my  limitations  to  let 
the  muscles  alone  in  all  such  cases  as  his,  even  if  the 
symptoms  were  more  indicative  of  a  muscular  cause 
than  in  this.  I  ordered  the  proper  cylinder  and  told 
him  to  treat  his  blepharitis,  for  whether  the  com- 
pression theory  be  true  or  not,  certainly  asthenopia 
comes  from  lid  irritation  in  some  cases;  advised 
strychnine  to  be  used  for  the  insufficiency  of  con- 
vergence and  the  effects  noted.  The  latter  treat- 
ment had  of  course  already  been  tried.  This 
physician  followed  the  first  two  suggestions,  and 
reported  with  apparent  delight  one  week  later,  be- 
fore he  left  for  home,  that  he  and  his  eyes  had  not 
been  so  comfortable  for  years.  There  was  no  change 
in  the  muscle  test.  It  is  doubtful  whether  those 
eyes  now  have  the  comfort  and  endurance  that 
would  be  likely  to  be  present  in  a  case  with  strong, 
well-balanced  ocular  muscles,  yet  a  moral  of  a  certain 
sort  may  be  drawn  from  the  history. 

It  may  be  well  here  to  call  attention  to  the  fact 
that  occasionally  cases  with  weak  externi  momen- 
tarily overcome  prisms  base  in  far  in  excess  of  those 
which  represent  the  real  muscular  power,  while 
rather  more  often  just  the  opposite  condition  obtains 
in  eyes  with  abnormally  strong  externi.  For  in- 
stance the  externi  may  overcome  prism  7.  or  8.  as 
the  test  is  first  made,  yet,  in  case  they  are  weak, 
diplopia  quickly  results  should  the  prism  be  kept 


74  Heterophorias  and  Insufficiencies. 

before  the  eyes,  after  which  it  is  found  that  weaker 
prisms  are  not  overcome ;  on  the  other  hand  with 
strong  externi  prisms  which  at  first  produce  diplopia 
are  overcome  soon  after,  and  divergence  may  thus 
turn  out  to  be  much  in  excess  of  that  which  a  rapid 
and  superficial  test  would  have  shown.  This  tendency 
to  concealment  of  latent  deviations  results  from  the 
very  nature  of  the  case;  these  eyes  are  not  only 
forced  into  binocular  fixation,  but  necessarily  also 
in  exercising  that  faculty  into  a  condition  which 
would  be  orthophoria  if  our  tests  should  not  succeed 
in  relaxing  the  strain  put  upon  the  weak  muscles. 
In  measuring  muscular  ability  endurance  should  be 
considered  more  than  temporary  strength. 


CHAPTER  IV. 

EXOPHORIA. 

THE  headache  of  exophoria  may  only  occur 
when  near  work  is  done,  or  is  increased  by 
near  work  unless  there  is  divergent  squint  for  near 
points.  It  may  be  frontal,  general,  or  consist  of 
pain  in  the  posterior  cervical  region,  and  be  accom- 
panied by  dizziness  or  nausea.  There  may  be  rapid 
exhaustion  of  the  eyes  for  near  work,  with  or  without 
headache,  from  exophoria  and  weak  convergence, 
and  sometimes  the  symptoms  may  be  produced  by 
simple  convergence  for  a  near  object  or  tests  with 
prisms  base  out.  This  production  of  symptoms  by 
prisms  which  bring  a  strain  upon  the  weaker  muscles 
is  not  confined  to  exophoria,  but  is  more  easily  de- 
tected in  this  than  in  other  deviations.  For  these 
reasons  weak  convergence  was  the  first  of  the  in- 
sufficiencies to  be  recognized,  and  has  received  an 
amount  of  attention  not  as  yet  accorded  to  the  more 
obscure  but  not  less  potential  muscular  weaknesses. 
As  will  be  noted  above,  the  asthenopic  symptoms 
in  esophoria  have  nothing  distinctive  of  the  source, 

75 


76  Heterophorias  and  Insufficiencies. 

since  combinations  of  other  muscular  and  refractive 
errors  may  cause  them. 

While  divergence  as  an  associated  action  has  un- 
doubted claims  to  a  cerebral  centre,  yet  I  am  posi- 
tive that  in  normal  conditions  it  cannot  be  forced 
beyond  a  well-known  limit  set  by  habit  and  the 
exercise  of  binocular  fixation.  I  accept  unquali- 
fiedly the  dictum  of  Hansen  Grut  that  divergence 
of  the  visual  lines  cannot  be  produced  at  will 
and  when  found  must  result  from  abnormality,  but 
that  latent  divergence  is  often  concealed  by  con- 
vergence which  exists  both  as  a  voluntary  and  reflex 
act. 

Exophoria  always  means  then  comparative  excess 
of  strength  of  the  externi,  or  of  divergence  (although 
not  necessarily  as  a  permanent  condition),  if  we  keep 
in  mind  the  fact  that  the  eyes  tested  at  nearer  points 
than  infinity  may  not  converge  for  the  test  distance. 
Thus  for  twenty  feet  if  parallelism  for  infinity  is 
present  and  fixation  is  for  infinite  distance,  either 
through  lack  of  accommodation  in  myopia  or  for 
any  other  cause,  it  will  take  about  a  I.  prism,  base 
in,  to  produce  vertical  equilibrium.  The  men  who 
originally  stated  that  the  difference  between  twenty 
feet  and  infinity  could  be  ignored  in  testing  the 
ocular  muscles  little  foresaw  that  this  would  some 
time  be  applied  to  tests  with  weak  prisms. 

Exophoria  of  I.  at  twenty  feet  I  have  often  seen 


A  Clinical  Study.  7  7 

occur  in  eyes  where  every  other  consideration  led 
me  to  consider  the  action  of  the  ocular  muscles 
normal;  more  than  that  amount  represents  a  real 
tendency  to  divergence,  and  with  exophoria  r.  only, 
manifest,  there  may  be  any  amount  latent. 

Accommodative  Exophoria. — Accommodative  ex- 
ophoria can  only  occur  with  myopia,  unless  it  is 
produced  by  too  strong  convex  lenses  in  hyper- 
metropia,  or  is  acquired  in  the  same  manner  from 
reading  glasses  in  presbyopia.  In  myopia  the 
exophoria  will  only  disappear  in  young  persons 
when  full  correction  is  ordered,  and  in  later  life  be- 
comes permanent,  although  in  an  occasional  case  it 
yields  somewhat  to  correction  of  the  refraction  in 
patients  up  to  the  age  of  forty  and  a  little  beyond 
it.  There  is  of  course  no  intention  on  my  part  to 
deny  that  certain  anatomical  conditions  assist  in  the 
production  of  exophoria  and  excessive  divergence 
in  myopic  cases.  In  cases  of  true  accommodative 
exophoria  there  is  likely  to  be  little  or  no  increase 
of  divergence  for  distance,  although  prism  conver- 
gence may  not  be  up  to  the  standard,  while  exopho- 
ria and  weakness  of  convergence  for  near  points  are 
out  of  proportion  to  these  conditions  for  distance. 
In  fact  it  is  the  old,  well-known  condition  of  relative 
divergence. 

These  cases  are  so  well  known  and  have  been  dis- 
cussed so  often,  that  anything  I  have  to  offer  may 


78  Heterophorias  and  Insufficiencies. 

be  briefly  stated.  To  prevent  exophoria  and  insuffi- 
ciency of  convergence  in  myopia  the  refraction 
should  be  fully  corrected ;  at  a  later  period  full  cor- 
rection, the  glass  being  worn  all  the  time,  will  give 
stimulation  to  the  convergence  and  favorable  pris- 
matic action  for  near  work.  Fortunately  this  class 
of  cases  are  not  troubled  much  with  muscular  as- 
thenopia  unless  there  is  an  evident  muscular  defect 
for  distance  which  admits  of  operation,  an  astigma- 
tism which  admits  of  correction,  or  nervous  exhaus- 
tion of  convergence  power  which  needs  appropriate 
general  treatment.  Perhaps  the  following  will  serve 
as  a  fairly  typical  case  of  accommodative  exophoria. 
An  athletic  schoolboy,  aged  fourteen  at  the  time  of 
my  first  examination,  October  i,  1898,  had  f$  o.u., 
with  sph.  —  1.25  ^  cyl.  —  .5  axis  105°  R.,  sph. 
1.50  L.  =  §§-.  Exophoria  3.,  no  asthenopia. 
Further  examination  of  refraction  and  muscles  con- 
sidered unnecessary.  The  glass  ordered  was  only 
worn  in  the  schoolroom,  and  on  December  22,  1899, 
the  myopia  had  increased  to  2.25  o.u.,  with  astig- 
matism as  before  in  the  right  eye.  Exophoria  4. 
As  I  supposed  this  to  be  a  good  sample  case  of  ac- 
commodative exophoria  the  muscles  were  further 
tested  in  order  to  give  the  tests  here.  Convergence 
at  twenty  feet,  12.,  easily  brought  up  to  25.  as  soon 
as  the  patient  was  shown  how  to  converge;  diver- 
gence, 7.  For  13",  exophoria  10.,  12.,  or  more;  a 


A  Clinical  Study.  79 

test  for  the  near  point  of  convergence  showed  fixa- 
tion at  first  at  10",  but  when  the  patient  was  told  to 
fix  his  attention  and  turn  the  eyes  in  for  the  pencil 
he  had  no  difficulty  in  converging  to  within  3"  and 
holding  the  eyes  in  that  position.  Cases  of  this 
sort  are,  in  my  opinion,  exophorias  without  muscu- 
lar insufficiency ;  they  are  more  likely  to  have  mus- 
cular asthenopia  from  overwork  than  those  cases  of 
myopia  in  which  the  eye  muscles  become  more 
correctly  adjusted  to  the  new  accommodative  con- 
ditions, unless  binocular  fixation  for  near  objects  is 
sacrificed. 

The  production  of  accommodative  exophoria  by 
means  of  convex  glasses  is  a  common  occurrence  and 
can  in  many  cases  be  avoided.  It  frequently  occurs 
from  full  correction  of  the  hypermetropia  found 
under  atropine,  and  over-correction  of  hypermetro- 
pia of  about  .50  in  cases  in  which  atropine  has  not 
been  used  is  of  no  uncommon  occurrence.  Patients 
sometimes  accept  an  over-correction  of  about  .50 
when  hypermetropic,  especially  if  after  each  eye  is 
tested  separately  the  highest  correction  is  forced 
with  both  eyes  open,  the  test  letters  with  the  glasses 
perhaps  appearing  somewhat  faded  or  washed  out, 
although  vision  is  not  diminished.  I  have  in  this 
manner  occasionally  succeeded  in  getting  a  stronger 
glass  to  correct  hypermetropia  than  could  be  ob- 
tained later  with  the  eyes  under  atropine.  Another 


8o  Heterophorias  and  Insufficiencies. 

class  of  cases  in  which  accommodative  exophoria 
occurs  are  those  in  which  (perhaps  under  atropine) 
the  spherical  lens  which  represents  the  meridian  of 
greatest  hypermetropia,  is  accepted  with  vision  of 
f$,  or  so,  while  the  addition  of  a  weak  concave 
cylinder  would  give  better  vision.  In  other  words, 
there  is  a  small  amount  of  astigmatism,  and  the 
spherical  over-correction  given  results  in  an  artificial 
myopic  astigmatism.  I  have  noted  several  cases 
during  the  past  year  in  which  exophoria  was  pro- 
duced or  increased  by  over-correction  of  hyperme- 
tropia and  prisms  base  in  had  been  added  to  the 
glasses  for  the  refraction,  the  total  result  to  the 
exophoria  being  an  increase ;  these  cases  had  asthe- 
nopic  symptoms  which  were  often  relieved  when  the 
convex  lenses  were  made  weaker  and  the  prisms  re- 
moved. Analysis  of  the  results  in  such  cases  show 
them  to  be  in  part  due  to  mental  causes  connected 
with  the  difference  in  vision,  in  part  to  refractive 
causes,  and  hence  the  effects  of  the  difference  in  cor- 
rection take  on  an  exaggerated  aspect  if  referred  to 
the  muscles  alone.  In  the  case  of  a  physician  with  a 
little  exophoria,  who  gave  up  medicine  twenty  years 
ago  because  he  found  no  glasses  to  relieve  his  asthe- 
nopia,  and  who  had  been  much  better  with  the  last 
glasses  ordered  for  him  than  any  previous  ones,  the 
first  glasses  (for  he  had  saved  them)  turned  out  to  be 
convex  cylinders  .75  and  .50  fitted  under  atropine; 


A  Clinical  Study.  81 

the  others  were  given  on  the  same  principle,  except 
the  last,  which  was  a  concave  cylinder,  opposite 
axis;  this  patient  has  since  been  able  to  use  his 
eyes  freely  and  comfortably  with  treatment  for  the 
muscular  error.  In  cases  in  which  the  effect  is  out 
of  all  proportion  to  the  cause  it  is  safe  to  refer 
something  to  the  imagination  of  the  patient. 

Accommodative  exophoria  from  glasses  also  occurs 
in  presbyopic  cases,  and  although  the  principles  in 
connection  with  accommodative  exophoria  as  first 
laid  down  by  Bonders  for  such  cases  cannot  be 
successfully  attacked,  if  any  man  expects  to  satisfy 
his  presbyopic  patients  by  any  attention  to  detail  in 
their  glasses  he  will  find  himself  sadly  disappointed, 
if  he  is  alive  to  the  results.  Many  of  these  patients 
demand  one  glass  with  which  they  can  see  at  far  and 
near  points,  and  may  consider  an  oculist  incompe- 
tent or  obstinate  if  he  fail  to  satisfy  what  they  con- 
sider a  reasonable  request.  Convergence  power  is 
usually  weak  in  presbyopes ;  convex  glasses  increase 
this  weakness  by  their  effect  upon  the  accommoda- 
tion, and  are  usually  centred  too  broadly,  adding 
an  adverse  prismatic  effect  to  the  other  difficulties. 
If  muscular  asthenopia  already  exists  from  weak 
convergence  the  glasses  may  be  centred  in  for  a  near 
reading  distance,  but  if  the  object  is  to  avoid  asthe- 
nopia from  glasses  it  will  be  safer  to  centre  them 
for  the  far  point  at  which  they  may  be  used,  since 

6 


82  Heterophorias  and  Insufficiencies. 

it  is  easier  to  exercise  convergence  than  divergence, 
for  evident  reasons.  Thus  suppose  a  glass  of  -|-  2.25 
about  15  mm.  in  front  of  each  cornea  or  30  mm.  in 
front  of  the  centre  of  rotation,  with  a  base  line  of 
60  mm.  It  would  be  safer  to  centre  these  glasses  at 
60  mm.  -  — -^  mm.  =  56  mm.,  i.  e.,  for  their  far 
point  of  1 8"  or  450  mm.  instead  of  nearer,  so  as  not  to 
increase  the  asthenopia  caused  by  looking  off  through 
them,  of  which  there  is  usually  so  much  complaint. 
Glasses  for  near  work  may  be  centred  by  sighting, 
in  a  similar  manner  to  those  for  distant  vision. 

There  is  one  point  in  addition  to  those  which 
have  received  attention  elsewhere  concerning  bifocal 
glasses,  and  that  is  that  the  principal  complaint  con- 
cerning these  glasses  is  of  the  distortion  of  objects 
and  diplopia  at  the  upper  part  of  the  junction  of 
that  portion  of  the  glass  used  for  distance  and  the 
paster.  While  the  formula  for  proper  centring  to 
prevent  this  prismatic  action  depends  upon  the  dis- 
tance of  the  upper  edge  of  the  paster  from  the 
geometrical  centre  of  the  whole  glass,  and  is  tedious 
to  work  out  mathematically,  it  is  a  comparatively 
easy  matter  for  the  manufacturer  to  cut  his  paster 
so  as  to  neutralize  prismatic  action  at  its  upper  edge. 
I  have  had  no  complaints  and  seen  no  bad  results 
due  to  the  symmetrical  prismatic  action  of  glasses 
of  equal  strength  decentred  upwards  or  down- 
wards. It  takes  more  knowledge  than  I  possess  to 


A  Clinical  Study.  83 

successfully  meet  the  demands  of  anisometropes 
who  desire  comfortable  non-distorting  bifocals. 

There  is  no  definite  agreement  regarding  what 
should  be  considered  normal  balance  for  the  ocular 
muscles  at  a  near  point,  such  as  the  reading  dis- 
tance. Among  healthy  young  adults  with  good 
muscular  strength  and  no  particular  refractive  error, 
who  do  not  unduly  use  their  eyes,  as  soldiers, 
orthophoria  is  the  rule  at  near  points  up  to  12"  or 
less.  This  is  indeed  the  best  condition,  yet  is 
found  only  exceptionally  among  patients  applying 
for  eye  treatment,  with  whom  exophoria  is  the  rule ; 
while  exophoria  at  a  near  point  may  easily  occur 
simply  from  relaxation  of  convergence  and  accom- 
modation, I  regard  exophoria  of  over  2.  at  13"  as  a 
sign  of  probable  weak  convergence,  and  feel  sure 
that  eyes  with  more  dynamical  divergence  than  this 
are  usually  more  or  less  asthenopic  from  weak  con- 
vergence. In  this  I  differ  from  some  other  observers, 
who  regard  4.  or  5.  of  exophoria  at  reading  distance 
as  having  no  significance. 

Much  has  been  said  regarding  the  production  of 
heterophoria  by  glasses,  but  nothing  much  about 
the  cases  in  which  the  eyes  are  forced  into  equilib- 
rium notwithstanding  the  adverse  prismatic  effect 
of  a  decentred  lens,  on  the  principle  which  causes 
normal  muscles  to  readjust  themselves  to  differences 
in  the  height  of  the  eyes.  The  following  case  is  an 


84  Heterophorias  and  Insufficiencies. 

example  of  accommodative  exophoria  to  which  was 
added  an  adverse  prismatic  action  of  over  6  D's  from 
decentred  glasses,  the  whole  error  being  rendered 
latent  by  spasm  of  the  weak  interni.  A  young  lady 
with  constant  severe  frontal  headache,  dizziness, 
which  had  lasted  for  years,  and  chorea,  was  wearing 
eye-glasses  with  —  5.50  o.u.  in  such  a  manner  that 
a  tight  spring  far  forward  on  the  nose  brought  the 
p.d.  (and  o.c.)  at  2",  the  base  line  being  2%" '.  V. 
O.U.  =  f$.  There  was  weak  convergence  for  near 
points,  but  at  20  feet  there  was  no  appreciable 
heterophoria,  convergence  14.,  divergence  7.  Sph. 
—  6.  at  2%"  o.c.  was  ordered,  and  one  month  later 
there  was  esophoria  3.,  convergence  12.,  divergence 
8.  at  20  feet.  Orthophoria  at  13"  with  convergence 
30.,  divergence  14.  The  headache  was  no  better 
and  I  began  to  doubt  my  diagnosis  of  exophoria 
and  spasm  of  convergence  from  improperly  centred 
glasses,  and  favored  choreic  spasm,  or  accommoda- 
tive spasm  from  concave  glasses,  more  than  I  had  at 
first ;  however  I  persisted,  and  one  month  after  the 
last  examination  exophoria  of  2.  with  convergence 
of  30.  and  divergence  of  10.  appeared  and  the  condi- 
tion of  the  eye  muscles  has  changed  but  little 
since;  the  headache  became  better  at  this  time,  and 
each  time  it  began  to  reappear  the  glasses  were 
ordered  with  o.c.  3  mm.  farther  out.  The  last  order, 
eighteen  months  after  the  first,  was  with  the 


A  Clinical  Study.  85 

o.c.    24".      Divergence   was  then   11.   with  an   ex- 

o  o 

ophoria  of  3.,  and  with  the  glasses  1.50  of  exophoria 
still  remains;  the  headache  has  not  returned  during 
the  year  and  a  half  since  then,  and  as  choreic  move- 
ments of  the  head  and  neck  have  disappeared,  or 
greatly  diminished,  the  correcting  glass  has  not 
been  further  disturbed,  or  other  eye  treatment  in- 
stituted in  the  vain  hope  of  helping  the  general 
nervous  difficulty. 

The  above  points  taken  from  the  written  history 
of  this  rather  unusual  case  do  not  show  the  main 
reason  why  a  diagnosis  of  spasm  of  the  interni  from 
misplaced  glasses  was  made  in  the  first  instance, 
and  I  add  from  a  clear  recollection  upon  that  matter 
that  the  orthophoria  at  the  first  test  was  shown 
without  the  glasses,  with  the  glasses  at  2"  o.c.,  or 
at  2-f"  o.c.,  with  the  same  action  upon  accommoda- 
tion, yet  a  variation  of  6  D's  of  prismatic  action. 
A  side  issue  in  the  case  was  the  demonstration 
of  the  fact  that  people  cannot  be  expected  to 
wear  the  nose-piece  of  eye-glasses  in  a  position  to 
which  habit  and  the  shape  of  the  nose  have  not 
previously  accustomed  them ;  if  a  new  position  of 
the  glass  is  desired  it  must  be  obtained  by  variation 
of  the  length  and  shape  of  the  posts  connecting  the 
nose-piece  with  the  glasses. 

Muscular  Exophoria. — Exophoria  with  insuffi- 
ciency of  the  interni  or  of  convergence  will  be 


86  Heterophorias  and  Insufficiencies. 

considered  in  the  next  chapter.  Exophoria  with 
excess  of  divergence  can  be  diagnosed  by  the 
tests  for  the  muscles  at  20  feet.  Divergence  of 
12.  or  more  always  constitutes  excess,  and  from  9. 
to  ii.  usually.  Convergence  commonly  decreases  as 
age  advances,  and  so  soon  as  divergence  excess  with 
asthenopia  is  known  to  be  permanent  there  should 
be  a  tenotomy  of  one  externus,  followed  if  neces- 
sary by  a  tenotomy  of  the  other.  This  should  be 
done  on  the  principles  already  described,  and  in 
marked  cases  of  excess  needs  to  be  complete,  and 
not  infrequently  the  attachments  of  the  insertion 
loosened,  to  produce  orthophoria  in  the  middle  of 
the  field,  with  divergence  of  7.  or  8.  A  single 
tenotomy  of  an  externus  carefully  done  upon  a  well- 
developed  muscle,  care  being  taken  to  divide  the 
tendon  at  its  insertion  and  not  loosen  the  attach- 
ments, will  seldom  give  more  than  5  D's  of  effect. 
As  a  rule  the  effect  at  the  time  of  operation  dimin- 
ishes but  little,  if  any,  at  a  later  period,  if  the  cut 
muscle  is  put  upon  the  stretch  for  a  few  days  after 
operation  by  forced  convergence;  the  most  effec- 
tive method  of  accomplishing  this  is  to  have  the 
eyes  converge  for  a  near  object,  as  the  finger, 
several  times  a  day,  and  once  a  day  have  this  done 
while  the  eyes  are  armed  with  converging  prisms ; 
observations  upon  cases  months  or  years  after  this 
operation  show  in  general  no  more  increase  of 


A  Clinical  Study.  87 

exophoria  than  usually  occurs  in  the  natural  course  of 
exophoria  without  operation.  As  a  result  of  this 
operation,  increase  in  the  power  of  convergence  is 
usually  more  than  the  decrease  of  divergence. 
There  is  less  apt  to  be  this  increased  conver- 
gence in  myopic  eyes,  and  in  those  where  the 
muscles  are  poorly  developed.  In  the  following 
case  increase  of  convergence  was  less  than  decrease 
of  divergence,  and  it  is  the  only  one  in  which  I 
have  seen  this  occur.  A  poorly  developed  school- 
boy of  thirteen  years  of  age,  with  myopia  of  1.75, 
showed  in  December,  1896,  exophoria  2.,  con- 
vergence 9.,  divergence  9.  Nine  months  later  exo- 
phoria 3.,  convergence  7.,  divergence  9.  Tenotomy 
of  the  left  externus  was  done  and  orthophoria  re- 
sulted. Six  weeks  later  there  was  exophoria  2., 
convergence  9.,  divergence  9.  Three  months  later 
tenotomy  of  the  right  externus,  resulting  a  week 
after  in  orthophoria,  convergence  10.,  divergence  6. ; 
one  month  later,  exophoria  .5,  convergence  9.,  di- 
vergence 8.  This  condition  has  continued  since, 
the  severe  headaches  which  the  patient  had  after 
studying  having  been  better,  but,  as  general  treat- 
ment including  arsenic  and  strychnine  has  been 
used,  it  is  doubtful  whether  the  operations  can  claim 
any  appreciable  credit. 

Another  case  of  a  similar  character  shows  that  so 
little  result  as  this  cannot  be  foretold.     This  was 


88  Heterophorias  and  Insufficiencies. 

the  case  of  a  man  of  twenty-five  with  severe  and 
constant  headache  made  worse  by  near  work.  He 
was  of  the  same  neurotic,  ill-developed  type,  had 
compound  myopic  astigmatism,  which  had  been 
carefully  corrected  one  year  before  I  saw  him  in 
April,  1898,  and  had  exophoria  4.,  convergence  6., 
divergence  10.  Tenotomy  of  the  left  externus  gave 
but  temporary  relief  as  orthophoria  only  lasted  a 
week;  so  one  month  after  the  first  operation  I 
over-corrected  the  exophoria  by  tenotomy  of  the 
right  externus,  attaining  esophoria  2.,  convergence 
14.,  divergence  3.,  changing  to  orthophoria  with 
convergence  16.,  divergence  7.,  in  two  months. 
The  proportions  changed  to  12.  versus  8.  nine 
months  after  the  second  operation,  when  the  patient 
reported  that  he  had  only  had  a  few  slight  head- 
aches when  he  was  tired  and  had  overused  his  eyes. 
In  contrast  to  these  let  me  give  the  most  marked 
case  of  increase  of  convergence  I  have  seen,  in  eyes 
with  hypermetropic  astigmatism  of  .50  in  one  eye 
and  .25  in  the  other.  A  young  lady  of  twenty-four 
years  came  to  me  in  May,  1899,  after  a  season  of 
operations  upon  the  ocular  muscles  done  for  the 
purpose  of  relieving  her  of  extreme  headaches,  dizzi- 
ness and  nausea.  She  was  wearing  sph.  -j-  I.  with 
prisms  of  2.50  base  in  over  each  eye  for  reading; 
exophoria  of  5.  at  13"  being  increased  to  8.  by  this 
combination.  She  had,  at  20  feet,  exophoria  of 


A  Clinical  Study.  89 

I  D.  with  the  phorometer,  7.  or  more  with  the 
Maddox  rod;  convergence  20.,  divergence  20.  I 
first  tried  correction  of  the  slight  astigmatism,  and 
removal  of  the  objectionable  glasses,  but  with  little 
relief,  so  three  weeks  later  I  divided  the  left  exter- 
nus;  all  the  exophoria  I  could  get  after  this  by  any 
test  was  4.,  and  the  first  result  and  that  five  months 
after  varied  only  I.,  convergence  going  to  38.,  diver- 
gence to  16.  This  improvement  in  the  eyes  and  a 
summer's  vacation  gave  no  relief  to  the  symptoms, 
although  general  tonic  treatment  had  been  kept  up. 
I  then  divided  the  right  externus,  and  the  patient  be- 
coming exhausted  and  faint  from  a  rather  prolonged 
operation  in  her  neurasthenic  state,  a  free  tenotomy 
left  2.  of  exophoria,  although  divergence  was  but  6. 
and  homonymous  diplopia  was  present  on  the  right 
side  of  the  field.  One  week  later,  as  convergence 
improved,  the  result  was  esophoria  2.,  convergence 
40.,  divergence  5.  In  one  month,  however,  there 
was  orthophoria  for  far  and  near  with  a  convergence 
of  65.,  divergence  9.,  at  20  feet.  The  action  of 
the  muscles  was  now  co-ordinate,  dizziness  and  nau- 
sea had  disappeared  and  the  general  headache  with 
them ;  the  distressing  pain  at  the  nape  of  the  neck 
had  not  yet  entirely  disappeared,  although  it  did 
soon  after,  the  patient  reporting  herself  well  two 
months  later  and  showing  the  same  muscular  condi- 
tion as  that  last  given.  In  this  case  reduction  of 


90  Heterophorias  and  Insufficiencies. 

divergence  II  D's  gave  increased  convergence  of 
45.  A  contrast  to  this  as  regards  result  to  the 
symptoms  before  a  good  muscle  test  was  obtained, 
yet  agreeing  as  regards  improvement  in  converging 
power,  is  shown  by  the  case  of  a  girl  of  nine  years, 
who  had  crossed  diplopia  under  a  red  glass,  and  in 
whom  I  did  free  tenotomy  of  the  left  externus,  with 
the  result  that  two  months  later  while  convergence 
for  near  work  had  improved,  at  20  feet  there  was 
convergence  of  2.  only,  divergence  of  20.  Eight 
months  later  there  was  convergence  of  12.,  diver- 
gence 14.  Severe  and  frequent  headaches  had  dis- 
appeared since  the  operation.  In  these  two  cases 
post-operative  hyperphoria  was  temporarily  pro- 
duced and  disappeared  in  a  week ;  a  not  very  un- 
common experience. 

In  contrast  to  these  complete  operations  giving 
slight  results  let  me  say  that  I  have  a  few  times  pro- 
duced convergent  squint  and  homonymous  diplopia 
before  an  externus  seemed  to  be  completely  divided, 
and  have  usually  advanced  the  cut  muscle  with  good 
result,  by  means  of  a  single  stitch  tightened  until 
orthophoria  in  the  centre  of  the  field  was  produced. 
In  one  case,  however,  the  patient  became  hysterical 
about  the  stitch  and  promised  faithfully  to  let  me 
do  anything  1  wished  in  the  way  of  an  operation 
later  if  I  would  remove  it.  As  I  wished  to  watch 
the  effect,  and  the  onus  was  on  her,  I  left  the  muscle 


A  Clinical  Study.  91 

as  it  was  by  drawing  out  the  stitch,  which  had  not 
yet  been  tied.  There  was,  strangely  enough,  no 
dizziness  following  the  operation,  the  headache 
which  had  not  yielded  to  correction  of  the  refrac- 
tion, or  other  treatment,  was  relieved,  and  two 
months  later  the  diplopia  could  not  be  obtained  at 
the  periphery  of  the  field  except  by  means  of  a  red 
glass.  A  test  four  months  after  this  showed  ortho- 
phoria. 

In  case  it  should  seem  strange  that  readjustment 
should  follow  in  some  cases  too  little,  in  others  too 
much  operative  effect,  let  me  say  that  in  the  former 
class  the  exercises  above  described  for  a  near  point 
are  used,  while  in  the  latter  near  work  is  prohibited 
for  a  time,  but  the  eyes  are  encouraged  to  fix  dis- 
tant objects.  This  small  detail  of  treatment  would 
be  of  little  use,  except  for  the  principle  that  people 
with  strong  desire  for  binocular  fixation  tend  to 
force  the  eyes  into  orthophoria  in  the  centre  of  the 
field,  as  soon  as  the  muscular  condition  will  per- 
mit of  such  a  thing ;  let  me  say,  however,  that  the 
above  cases  are  for  me  the  exception ;  in  most  of  the 
others  orthophoria  was  the  primary  result  of  the  first 
operation.  In  such  a  case,  if  the  effect  decreases 
later,  when  a  second  operation  is  done  I  over-correct 
by  an  amount  equal  to  the  decrease  which  occurred 
after  the  first  operation. 

Exophoria  of  4.  or  more  with  more  than   12.  of 


92  Hetcrophorias  and  Insufficiencies. 

divergence  will  usually  require  an  apparently  com- 
plete tenotomy.  By  apparently,  I  mean  that  it  is 
difficult  to  cut  across  the  tendon  of  a  muscle  with- 
out loosening  the  subconjunctival  tissue,  or  the  at- 
tachments of  the  muscle  to  the  capsule  of  Tenon, 
through  a  small  opening  in  the  conjunctiva,  and  be 
sure  of  the  complete  character  of  the  division,  even 
when  the  line  of  insertion  to  the  sclera  can  be  seen ; 
a  small  band  of  fibres,  deep  and  peripheral,  may 
easily  escape  notice.  It  should  be  remembered 
that  the  object  is  to  remove  the  muscular  difficulty, 
not  to  prove  the  division  of  a  muscle.  In  weaker 
muscles  tenotomies  which  only  partially  divide  the 
tendon  will  produce  results ;  as  these  cases  are  often 
of  the  neurasthenic  type,  I  generally  avoid  operation 
upon  them  and  cannot  speak  so  definitely  of  them  as 
of  the  class  in  which  I  find  that  division  of  the  ten- 
don nearly,  or  completely,  in  such  a  way  as  to  avoid 
too  much  retraction  of  the  muscle,  is  necessary  to 
obtain  a  definite  result. 

It  is  by  no  means  easy  to  tell  in  advance  how 
much  a  muscle  will  retract,  hence  the  necessity  of 
graduating  the  operation  by  testing  the  eyes  at  inter- 
vals. Every  competent  operator  uses  this  principle 
in  cases  of  squint  when  he  looks  at  the  eyes  to  see 
whether  he  has  advancement  or  tenotomy  enough  to 
reduce  the  deformity;  in  this  case  he  is  operating 
for  appearance,  in  the  other  for  muscular  balance. 


A  Clinical  Study.  93 

In  exophoria  cases  it  is  well  to  take  the  desired 
strength  of  divergence  as  a  guide  in  operating  as 
well  as  the  production  of  orthophoria. 

It  is  very  important  to  consider  hyperphoria  in  its 
bearing  upon  exophoria  and  esophoria.  The  lateral 
deviations  may  improve  or  disappear  when  hyper- 
phoria is  corrected,  or  they  may  require  further  cor- 
rection ;  the  method  already  described  of  correcting 
the  hyperphoria  with  prisms,  then  testing  the  lateral 
balance  with  the  rod,  also  trying  the  effect  upon 
convergence  and  divergence,  gives  valuable  informa- 
tion but  is  not  infallible. 

Neurasthenia  as  a  result  of  operations  upon  the 
eye  muscles  is  not  uncommon,  from  the  nervous 
anxiety  and  traumatism,  and  it  is  well  for  the  opera- 
tor to  get  through  by  means  of  as  few  operations  as 
possible.  If  the  symptoms  are  no  better  after  a 
couple  of  operations,  it  is  just  as  well  to  inquire  and 
determine  whether  a  neurasthenic  asthenopia  is  not 
replacing  a  muscular  asthenopia,  and  treat  the  case 
accordingly. 


CHAPTER  V. 

INSUFFICIENCY  OF  CONVERGENCE;   NEURASTHENIC 

MUSCULAR  ASTHENOPIA;   INEFFICIENCY   OF 

THE   OCULAR   MUSCLES. 

IT  has  been  a  time-honored  custom  among  oph- 
thalmologists, to  group  all  cases  of  asthenopia 
of  which  they  failed  to  understand  the  origin  as 
neurasthenic.  In  the  United  States  a  race  of  rest- 
less adventurous  explorers,  fighters  of  Indians  and 
revolutionists,  have,  in  the  persons  of  their  descend- 
ants and  successors,  taken  to  city  life,  books,  physi- 
cal appliances,  artistic  paraphernalia,  steam  heat, 
and  other  appurtenances  of  what  they  call  education 
and  civilization,  with  the  same  result  that  obtains 
when  the  country-bred  boy  settles  down  to  sedentary 
city  life — trouble  with  the  digestion,  circulation,  and 
nervous  system.  The  first  attempts  at  imitating 
foreign  civilization  in  this  country  resulted  twenty- 
five  or  more  years  ago  in  the  thin,  pale,  nervous 
young  girl;  as  admiration  for  the  civilization  of 
France  began  to  be  replaced  by  imitation  of  the 
English  style  of  life  this  type  of  woman  began  to 

94 


A  Clinical  Study.  95 

be  replaced  by  the  larger,  stronger,  rosier  type  in 
which  forced  development  of  the  bones,  muscles, 
and  circulation  was  expected  to  properly  adjust  the 
balance  in  the  forced  brain  and  nervous  system, 
with  the  result  that  nervous  irritability  with  some 
energy  and  endurance  began  to  give  way  to  neuras- 
thenia and  emotional  disturbances  of  the  nervous 
system.  In  the  first  type  by  means  of  tonics,  nour- 
ishing food,  fresh  air,  and  exercise  we  expect  to 
meet  the  indications ;  if  in  the  course  of  a  generation 
or  two  the  second  is  the  result  of  this  method,  what 
next  ? 

The  undoubted  soundness  of  the  view  that  atten- 
tion to  hygiene  is  the  key  to  development  of  the 
nervous  system  as  well  as  the  other  forms  of  tissue 
cannot  be  questioned ;  yet  the  occurrence  of  weak- 
ness in  the  ocular  muscles  with  other  undoubted 
evidences  of  lack  of  force,  in  the  well-nourished  and 
apparently  well-developed  American  youth  of  to- 
day, show  that  nervous  degeneration  cannot  always 
be  successfully  combated  by  a  general  knowledge 
that  nourishing  food,  fresh  air,  and  exercise  tend 
to  develop  the  human  animal. 

The  main  point  to  be  insisted  upon  here  is  that  a 
neurasthenic  patient  with  muscular  asthenopia  is 
not  of  necessity  a  case  of  neurasthenic  muscular 
asthenopia.  The  more  neurotic  a  person  is  the 
more  likely  he  or  she  is  to  suffer  from  nervous 


96  Heterophorias  and  Insufficiencies. 

symptoms  referable  to  ocular  defects,  just  as  a  case 
of  chronic  gastric  catarrh  has  more  dizziness  and 
nausea  from  eye  strain  than  one  with  better  diges- 
tion. Occasionally  muscular  and  nervous  signs  of 
exhaustion  occur  from  excessive  use  of  the  eyes, 
with  hyperesthesia  retinae  and  even  displacement 
fields  of  vision,  in  persons  who  have  not  shown  evi- 
dences of  exhaustion  in  any  other  function  than  that 
of  vision ;  as  the  exhaustion  is  mainly  of  nervous 
tissue  of  the  eyes  and  their  cerebral  connections, 
these  are  properly  to  be  considered  as  cases  of  neu- 
rasthenic asthenopia,  although  general  evidences  of 
nerve  exhaustion  are  absent.  Perhaps  "  neurasthe- 
nopia  "  would  be  a  proper  term  for  them. 

The  type  of  muscular  weakness  which  belongs 
to  the  neurasthenic  is  that  known  as  insufficiency  of 
convergence,  or  defective  amplitude  of  convergence; 
this  latter  term,  with  its  positive  and  negative  fac- 
tors, is  proper  but  formidable,  and  studies  already 
made  under  this  head  are  of  little  clinical  value  as 
regards  diagnosis  and  treatment  of  heterophoria.  I 
here  take  the  liberty  of  proposing  the  term  "  Ineffi- 
ciency of  the  Ocular  Muscles"  for  the  class  of  cases 
to  be  described  ;  inefficiency  means  lack  of  power,  or 
the  desire  for  power,  and  exactly  denotes  the  con- 
dition of  weak  muscular  action  arising  from  lack  of 
development  of  muscles  or  of  nervous  tissue,  fatigue 
and  lack  of  energy,  or  want  of  ambition,  which 


A  Clinical  Study.  97 

characterizes  neurasthenic  muscular  asthenopia. 
We  often  meet  in  the  American  youth  of  to-day 
and  in  others  broken  down  by  worry  or  illness,  such 
conditions  of  the  ocular  muscles  as  follows:  Ortho- 
phoria  or  esophoria  i.  to  2.,  convergence  9.  to  12., 
divergence  3.,  4.,  or  5. ;  orthophoria  or  exophoria,  I. 
or  2.,  convergence  from  6.  to  8.,  divergence  from  8.  to 
6.  Fixation  for  a  near  point  is  weak  and  inadequate, 
with  exophoria  at  13"  from  a  few  dioptrics  up  to 
actual  divergence  of  the  lines  of  fixation.  Sursum- 
duction  usually  I.  or  1.50.  This  condition  may  be 
acquired,  and  if  due  to  temporary  general  or  ocular 
fatigue  consist  merely  of  a  relative  insufficiency  of 
convergence,  with  little  or  no  weakness  or  excess 
of  divergence,  and  yield  rather  easily  to  ocular  rest 
and  general  treatment  with  strychnine.  More  often 
the  condition  is  permanent,  both  the  ocular  mus- 
cles and  the  brain  centres  being  undeveloped,  and 
I  regard  this  condition  as  shown  by  inefficiency 
of  the  ocular  muscles  as  one  of  the  stigmata  of 
degeneration. 

Occasionally  the  apparent  lack  of  muscular  power 
is  simply  a  sign  of  constitutional  laziness  and  in 
such  cases  will  not  cause  pain  and  discomfort ; 
sometimes  there  is  a  hysterical  element,  more  or 
less  latent,  and  the  muscular  strength  is  variable. 
Variation  in  the  power  of  convergence  and  diver- 
gence, except  in  cases  of  hyperphoria,  or  functional 


98  Heterophorias  and  Insufficiencies. 

or  organic  nervous  disease,  does  not  seem  to  occur 
to  any  extent  in  my  cases  of  late  years,  perhaps 
because  the  routine  tests  are  made  over  and  over 
under  the  same  conditions  as  regards  the  manner  of 
testing,  and  with  precautions  against  variation. 

In  neurasthenic  subjects  the  weak  ocular  muscles, 
sensitive  retinae,  irritable  reflex  centres,  and  gener- 
ally inefficient  muscular  and  nervous  force  cause 
undue  susceptibility  to  slight  physical  variations 
affecting  the  eyes,  while  the  cerebral  condition  is 
often  such  that  general  effects  from  slight  local 
causes  may  be  exaggerated,  distorted,  or  imagined ; 
in  treating  such  cases,  although  the  underlying 
principles  are  the  same  as  in  others,  the  point  of 
view  should  change  so  materially  that  they  must  of 
necessity  be  considered  as  a  separate  class.  For 
them  the  use  of  tinted  glasses  should  be  discour- 
aged ;  the  chemical  rays  of  light,  the  most  if  not  the 
only  injurious  ones  to  the  eyes,  do  not  penetrate 
glass  to  any  extent,  irradiation  of  light  increases 
with  refractive  error,  and  hence  correcting  glasses 
are  indicated  if  the  patient's  prejudices  and  nervous 
condition  will  permit  glasses  to  be  worn.  Strong 
glasses  may  not  be  borne,  even  if  they  barely  correct 
manifest  error,  and  care  must  be  taken  to  guard 
against  strong  or  adverse  prismatic  effects.  In  a 
few  cases  in  which  operations  seemed  indicated  to 
me  I  found  the  muscles  ill  developed,  as  might  be 


A  Clinical  Study.  99 

supposed  from  the  nature  of  the  cases  and  the  re- 
sults of  tests  for  muscular  power;  such  muscles  may 
be  badly  injured  by  tenotomy  and  cannot  be  much 
strengthened  by  advancement.  If  lack  of  nervous 
impulse  is  the  cause  of  the  inefficiency,  or  it  is  due 
to  temporary  exhaustion  of  muscular  or  nervous 
force  where  the  muscles  are  well  developed,  opera- 
tions are  surely  not  indicated.  Since  operations  are 
of  little  or  no  use  for  the  inefficiency,  and  may  be 
harmful  to  the  neurasthenia,  they  could  only  apply 
to  the  correction  of  slight  heterophorias  when  such 
are  present  and  cannot  be  successfully  treated  in 
some  other  manner;  they  would,  therefore,  be  pref- 
erably postponed  until  general  treatment  has  failed 
to  relieve  the  asthenopia,  and  the  general  strength 
of  the  ocular  muscles  has  reached  a  maximum. 

It  must  be  kept  in  mind  that  one  form  of  insuffi- 
ciency yet  remained  to  be  considered  when  we 
reached  this  chapter,  insufficiency  of  the  interni,  or 
convergence,  without  excess  of  divergence,  not  ac- 
companying hyperphoria,  nor  accommodative,  and 
that  this  condition  is  neurasthenic  and  constitutes 
inefficiency  of  the  ocular  muscles.  Although,  as  in 
the  first  case  cited  under  the  heading  exophoria,  it 
may  be  seen  that  advancement  of  the  interni  appears 
to  be  indicated,  this  operation  at  the  best  may 
cause  too  much  post-operative  annoyance  to  be  ap- 
propriate to  the  neurasthenic  condition,  and  we  may 


ioo  Hcterophorias  and  Insufficiencies. 

be  compelled  to  confine  ourselves,  when  an  opera- 
tion is  justifiable,  to  cutting  some  fibres  of  a  superior 
or  external  rectus  for  the  correction  of  hyperphoria 
or  exophoria,  which  would  be  more  formidable  ex- 
cept that  in  cases  of  inefficiency  the  operation  is  a 
slight  one,  complete  division  of  the  tendon  seldom 
being  necessary. 

Extensive  discussion  of  general  treatment  is  be- 
yond the  province  of  this  work.  Strychnine  is  the 
general  remedy  most  applicable  to  strengthen  mus- 
cular and  reflex  action.  It  is  given  at  first  in  small 
doses,  then  the  dose  is  increased  from  time  to  time. 
It  seems  to  me  that  in  this  manner  we  find  just  the 
dose  that  may  be  borne  by  a  patient,  not  that  we 
induce  toleration  for  the  drug.  The  remedy  bene- 
fits some  cases  quickly,  others  slowly,  others  not  at 
all;  cases  of  orthophoria  with  insufficiency  of  con- 
vergence, due  to  fatigue  from  excessive  eye  work, 
do  best  with  it,  as  previously  stated ;  cases  of 
esophoria  with  general  nervous  irritability  do  much 
less  well.  Certain  general  conditions  are  a  contra- 
indication for  strychnine,  noticeably  arteriosclerosis 
with  high  arterial  tension. 

Decision  regarding  the  comparative  merits  and 
proper  amount  and  character  of  rest  and  exercise  in 
the  general  treatment  of  these  cases  requires  much 
experience  and  nicety  of  judgment.  It  seems  evi- 
dent, however,  that  rest  from  that  which  fatigues  or 


A  Clinical  Study.  101 

irritates  the  nervous  system,  or  rest  to  an  overused 
structure  or  organ,  would  be,  of  necessity,  indicated. 
It  is  hard  for  some  of  us  to  see  any  rational  treat- 
ment for  the  eye  with  structural  or  functional  weak- 
ness, suffering  from  symptoms  brought  on  by  strain 
of  the  weak  part  from  overuse,  not  founded  upon 
rest  for  the  weary  organ.  Neuralgias  in  general  are 
treated  by  attempts  to  improve  the  health  and  give 
rest  to  the  painful  part.  Since  the  eyes  are  con- 
stantly in  use  when  the  lids  are  open,  we  are  unable 
to  obtain  absolute  rest  without  imperiling  the  gen- 
eral health ;  so  we  partially  rest  the  ciliary  muscle 
and  meet  visual  and  retinal  indications  by  correcting 
the  refraction,  and  attempt  to  give  rest  to  the  weak 
muscles  by  means  of  prisms,  while  we  try  to  obtain 
a  proper  muscular  balance  by  various  methods.  It 
is  not  the  insufficiency  which  causes  asthenopia  but 
use  of  the  insufficient  muscles;  insufficiency  of  the 
externi  gives  rise  to  headache  with  the  most  certainty 
when  the  eyes  are  used  to  look  at  outside  objects 
from  the  windows  of  a  moving  train,  while  if  no  in- 
sufficiency exists  for  a  near  point  the  eyes  may  be 
used  for  reading,  upon  the  same  journey,  without 
discomfort;  reading  from  a  prone  position  causes 
trouble  especially,  or  solely,  in  cases  of  hyperphoria. 
In  inefficiency  the  converging  power  suffers  most; 
the  condition  precedes  the  asthenopia,  apparently, 
as  the  weakness  is  congenital,  or  acquired  from 


IO2  Heterophorias  and  Insufficiencies. 

worry,  illness,  or  the  wear  and  tear  of  surgical  in- 
juries or  operations,  in  the  latter  cases  the  asthe- 
nopia  and  headache  beginning  after  hard  use  of  the 
eyes  for  reading,  or  other  near  work,  during  conva- 
lescence. Headache,  dizziness,  nausea,  conjunctival 
congestion,  and  pain  at  the  back  of  the  neck  are 
most  in  evidence  with  convergence. 

Should  it  appear  that  we  are  indulging  in  an  un- 
necessary amount  of  detail  in  order  to  show  that 
rest  is  so  important  in  the  treatment  of  exhausted 
ocular  muscles,  it  must  be  remembered  that  there 
was  a  time,  perhaps  forgotten  by  a  younger  genera- 
tion, when  a  well-known  American  ophthalmologist 
instituted  a  treatment  for  asthenopia  consisting  of 
ocular  gymnastics  (and  ointments  for  the  forehead), 
which  was  received  by  some  with  great  enthusiasm 
and  expected  by  them  to  relieve  all  forms  of  eye 
strain  not  evidently  accommodative ;  also,  that  forms 
of  exercise  for  the  ocular  muscles  are  still  in  use  with 
many  statements  on  record  regarding  the  increased 
strength  obtained,  as  shown  by  tests  and  relief  to 
symptoms.  The  first  claim  has  been  considered  in 
an  early  portion  of  this  work;  as  to  the  second, 
neurasthenia  is  essentially  a  chronic  condition  with 
intermittent  symptoms,  and  statements  regarding 
relief  to  symptoms  are  to  be  received  with  caution ; 
they  may,  in  fact,  be  a  measure  of  the  self-satisfac- 
tion of  the  man  presenting  them,  or  an  expression 


A  Clinical  Study.  103 

of  an  evident  appreciation  of  his  efforts  by  his 
patients,  rather  than  an  actual  count  of  tangible  re- 
sults— which  is  well-nigh  impossible  to  make  in  cases 
with  subjective  symptoms. 

The  general  rule  should  be  that  eyes  are  not  to 
be  used  for  near  work  after  they  show  the  slightest 
signs  of  fatigue.  When,  as  in  my  cases,  tests  for 
convergence  bear  a  definite  relation  to  the  ability 
for  near  work,  they  may  be  used  as  a  guide.  Thus, 
with  prism  convergence  of  8  D's  for  distance,  the 
eyes  are  to  be  used  at  first  not  over  five  minutes 
twice  a  day,  this  time  to  be  increased  with  increased 
convergence  power,  until  with  16  D's  the  eyes  are 
used  for  near  work  half  an  hour  four  times  a  day. 

We  have  already  noted  the  effect  of  emotion 
upon  the  ocular  muscles,  and  incidentally  it  has  been 
suggested  that  those  emotions  which  cause  excite- 
ment or  irritability  induce  spasm  of  strong  muscles, 
while  those  which  cause  exhaustion  increase  insuffi- 
ciency ;  in  this  way  latent  heterophoria  may  become 
manifest,  or  pseudo-heterophoria  may  be  produced. 
Nervous  young  women  sometimes  dread  an  examina- 
tion of  the  eyes,  and  having  a  little  asthenopia,  are 
fearful  that  this  signifies  some  dread  disease.  Fear 
not  only  dilates  the  pupil,  but  relaxes  accommoda- 
tion and  convergence.  This  condition  being  limited 
in  duration,  certain  cases  which  show  inefficiency 
of  the  ocular  muscles  at  a  first  test  will  show 


104  Heterophorias  and  Insufficiencies. 

improvement  of  convergence  at  a  later  period,  with- 
out regard  to  treatment.  The  contradictory  in- 
dications to  be  met  in  treating  the  asthenopia  and 
convincing  the  patient  that  there  is  nothing  the 
matter  with  the  eyes,  may  sometimes  require  mental 
more  than  direct  medical  treatment. 

When  glasses  are  worn,  especially  convex  ones,  a 
new  relation  is  set  up  between  accommodation  and 
convergence,  and  muscular  asthenopia  may  result, 
the  condition  being  more  intractable  as  age  ad- 
vances, and  most  complained  of  by  neurasthenic 
patients.  To  overcome  the  difficulty  it  is  absolutely 
necessary  that  the  eyes  should  converge  with  the 
glasses,  and  if  a  neurotic  patient  insists  upon  the 
impossibility  of  using  the  eyes  for  near  work,  con- 
verging exercises  with  the  finger  or  with  prisms  may 
possibly  be  indicated.  These  cases  may  be  diag- 
nosed by  the  increase  of  heterophoria  with  glasses  at 
a  near  point,  when  the  centres  are  in  the  lines  of 
fixation  for  that  point. 

The  division  of  asthenopia  into  retinal,  from  gen- 
eral disease,  accommodative,  from  errors  of  refraction, 
and  muscular  is  not  sufficiently  comprehensive.  It 
does  not  include  the  effect  of  certain  materials  upon 
the  eyes,  as,  for  example,  glazed  paper ;  operatives 
who  make  white  boxes  with  this  material  suffer  from 
eye  strain  which  ceases  with  a  change  of  occupa- 
tion. Other  causes  of  asthenopia,  such  as  a  bent 


A  Clinical  Study.  105 

position  of  the  head,  use  of  the  eyes  immediately 
after  meals,  poor  position  and  character  of  the 
illumination  used,  are  also  not  included  in  the  above 
classification.  We  all  know  that  somewhat  modified 
daylight  from  above  and  to  the  left  and  rear  is  de- 
sirable, but  the  character  of  the  artificial  illumina- 
tion which  is  least  injurious  to  the  eyes  is  still  in 
doubt.  A  belief  in  the  bad  effects  of  insufficient 
illumination  is  well-nigh  universal;  that  poor  light 
causes  ocular  discomfort  is  perfectly  evident,  yet  it 
is  difficult  to  see  how  it  could  do  the  harm,  func- 
tionally or  organically,  that  must  come  from  excess 
of  illumination.  In  the  medium  limits  of  illumina- 
tion, where  increased  light  causes  increase  of  vision, 
the  latter  increases  only  about  as  the  logarithm  of 
the  former,  and  the  excess  of  light  is  injurious  to  the 
retina.  If  we  look  at  the  history  of  any  nation,  or  the 
comparative  history  of  all,  we  see  without  exception 
that  asthenopia  increases  directly  with  the  increase 
in  amount  and  intensity  of  artificial  illumination. 
Here  we  have  the  combination  of  causes  which  pro- 
duce "  neurasthenopia  "  or  ocular  exhaustion,  with- 
out regard  to  the  nature  of  the  defects  existing  in 
the  structure  or  dynamics  of  the  eyes:  the  artificial 
life  which  goes  with  artificial  illumination,  the  ability 
to  continue  using  the  eyes  when  they  are  fatigued 
and  should  be  rested,  and  the  direct  chemical  effect 
of  improper  light  upon  the  exhausted  retina. 


106  Heterophorias  and  Insufficiencies. 

It  may  seem  that  these  and  some  other  considera- 
tions herein  presented  have  little,  if  any,  direct 
bearing  upon  the  ocular  muscles.  This  book  is  not 
intended  for  those  who  can  treat  asthenopia  success- 
fully by  ignoring  the  ocular  muscles,  or  those  who 
can  obtain  the  same  happy  result  through  these 
muscles  alone. 

118  EAST  720  STREET,  NEW  YORK, 
March  5,  1900. 


THE  LIBRj 
UNIVERSITY  OF  CALIFORNIA 
LOS  ANGELES 


A     000414560     3 


